Never Run Dry: Your Automated Maker Supply Tracker

Productivity beginner 10 min read

Electronics workshop with tools and components on a workbench

You’ve got eight rolls of PLA filament in three different colors, a half-used bottle of resin that’s been sitting open for two months, two sheets of birch plywood that you’re pretty sure are still good, and a bucket of wood stain that you have no idea how old it is. You started a new project and realized you’re short on the matte black filament you need — which means either a $25 emergency order or scrounging through your “organization system” (a pile in the corner).

Meanwhile, you bought 2kg of resin last November thinking it would last forever, and you have no idea if it’s still usable. You also can’t remember if you bought that pack of nozzles two months ago because you actually needed them or just thought they were a good idea.

This is the maker’s invisible tax. Materials leak, expire, get forgotten, and get bought at inconvenient moments. OpenClaw can be your shop inventory manager.

What This Solves

Emergency supply runs. The midnight filament shortage. The weekend brewing project halted because you’re out of Starsan. The wood stain that seemed fine until it didn’t cure. OpenClaw tracks what you have and warns you before you run out.

Materials going stale. Resin has a shelf life (typically 6-12 months after opening, longer sealed). Wood finish can go bad. Even filament absorbs moisture over time and prints poorly. The system monitors aging materials and tells you when to use it or toss it.

Bulk buying FOMO. When you do need to restock, should you buy one roll or five? OpenClaw tracks your consumption rate and tells you whether bulk makes sense or whether you’ll end up with abandoned inventory.

Cost blindness. You know you spent $300 on 3D printing supplies last quarter, but what did it actually go to? The system can break down spending by category and project so you understand where your hobby money is actually going.

Reorder paralysis. For specialty items (specific resin brands, niche hardware), you want to reorder when you remember — not when you’re already out. OpenClaw reminds you while you still have buffer.

How It Works

1. Your Inventory File

You maintain a structured YAML file with everything in your shop:

# ~/maker/inventory.yaml

supplies:
  # --- 3D Printing ---
  - name: "Polymaker PLA Matte Black"
    category: filament
    color: "#1a1a1a"
    weight_grams: 1000
    remaining_grams: 620
    purchase_date: 2026-05-12
    expiration_notes: "PLA: ~2 years shelf life if sealed, moisture-sensitive"
    cost_per_roll: 24.99
    supplier: "Polymaker (Amazon)"
    reorder_threshold_grams: 200
    reorder_qty_recommended: 2  # buy 2 more when you hit threshold
    current_project: "Desk organizers"

  - name: "Elegoo ABS+ Red"
    category: filament
    color: "#cc2222"
    weight_grams: 1000
    remaining_grams: 340
    purchase_date: 2026-06-01
    expiration_notes: "ABS+: absorbs moisture, seal tightly"
    cost_per_roll: 27.99
    supplier: "Elegoo"
    reorder_threshold_grams: 300
    reorder_qty_recommended: 3
    current_project: null

  - name: "Elegoo ABS+ Red (opened, partial)"
    category: filament
    opened_date: 2026-06-10
    weight_grams: 340  # estimated from remaining on spool
    notes: "Has been sitting open, may need drying before use"
    moisture_risk: true

  - name: "Elegoo Standard Resin"
    category: resin
    color: clear
    volume_ml: 1000
    remaining_ml: 580
    purchase_date: 2026-01-20
    opened_date: 2026-02-15
    expiration_notes: "Shelf life ~12 months opened, longer sealed"
    cost: 29.99
    supplier: "Elegoo"
    reorder_threshold_ml: 200
    reorder_qty_recommended: 2
    storage_location: "Dark cabinet, sealed"
    current_project: "Miniatures batch 2"

  - name: "Polymaker PLA Silk Gold"
    category: filament
    color: "#d4a017"
    weight_grams: 1000
    remaining_grams: 940
    purchase_date: 2026-07-01
    cost_per_roll: 26.99
    supplier: "Polymaker (Amazon)"
    reorder_threshold_grams: 200
    reorder_qty_recommended: 1
    current_project: null
    notes: "Not opened yet, still vacuum sealed"

  # --- Woodworking ---
  - name: "Birch Plywood 18mm"
    category: wood
    dimensions: "24x24 inch sheets"
    quantity: 2
    thickness_mm: 18
    purchase_date: 2026-06-15
    notes: "Stored flat, appears undamaged"
    cost: 38.00
    supplier: "Local Hardwoods"
    reorder_threshold: 1
    reorder_qty_recommended: 4
    current_project: "Coffee table"

  - name: "Minwax Wood Finish Ebony"
    category: finish
    volume_ml: 355
    remaining_ml: 180
    purchase_date: 2025-04-01
    opened_date: 2025-04-20
    expiration_notes: "Oil-based, 4+ years sealed, 1-2 years opened"
    cost: 12.99
    supplier: "Home Depot"
    reorder_threshold_ml: 100
    reorder_qty_recommended: 1
    notes: "Slightly thicker than fresh — stir well before use"

  # --- Homebrewing ---
  - name: "Starsan Acid Sanitizer"
    category: brewing_sanitizer
    volume_ml: 946
    remaining_ml: 420
    purchase_date: 2026-03-01
    expiration_notes: "Stable 1 year+ if sealed, 3 months once diluted"
    cost: 19.99
    supplier: "Northern Brewer"
    reorder_threshold_ml: 200
    reorder_qty_recommended: 2  # buy 2, concentrate keeps
    notes: "Stored in original bottle, cap tight"

  - name: "Muntons Brew Enhancer 3"
    category: brewing_ingredient
    weight_grams: 500
    remaining_grams: 0  # used on batch #7
    purchase_date: 2026-05-10
    expiration_notes: "Dry ingredients, ~2 years shelf life"
    cost: 6.99
    supplier: "Northern Brewer"
    notes: "Finished — reorder before next IPA brew"
    current_project: null

projects:
  - name: "Desk Organizer Set"
    category: 3d_printing
    started: 2026-07-15
    filament_used_grams: 380
    estimated_cost: 9.50
    status: in_progress
    notes: "3-part modular system, matte black PLA"

  - name: "Coffee Table"
    category: woodworking
    started: 2026-06-01
    materials_cost: 85.00
    estimated_hours: 12
    status: in_progress
    notes: "Birch ply top, walnut edge trim planned"

usage_rates:
  # Calculated from history
  "Polymaker PLA Matte Black":
    grams_per_week_avg: 45
    rolls_per_quarter: 1.4
  "Elegoo ABS+ Red":
    grams_per_week_avg: 80  # used heavily last month
    rolls_per_quarter: 2.5
  "Elegoo Standard Resin":
    ml_per_week_avg: 60
    bottles_per_quarter: 1.1
  "Starsan Acid Sanitizer":
    ml_per_brew_day: 30
    brew_days_per_month: 2

This is the source of truth. Start with the materials you use most; add the rest over time.

2. Weekly Inventory Check

A weekly cron job (Saturday morning works well) runs through your inventory:

# Cron: Saturday 9am
# 1. Check each item against reorder thresholds
# 2. Flag items approaching expiration
# 3. Calculate usage rates from recent projects
# 4. Summary report to Telegram

Your Saturday morning message:

🛠️ Maker Supply Report — Aug 9

Low stock (reorder soon):

  • Elegoo ABS+ Red: 340g remaining (threshold: 300g, but project active — monitor)
  • Elegoo Standard Resin: 580ml remaining (threshold: 200ml, no active project)

Expiring soon:

  • Elegoo Standard Resin: opened Feb 15, ~12 months opened shelf life — use within 6 weeks or treat as suspect

Bulk buy analysis:

  • PLA Silk Gold: you use ~45g/week of matte black, ~80g/week of ABS+ red. Buying 3 rolls of ABS+ red at once = ~37 days supply. If your project cadence holds, that’s fine.
  • Starsan: you’re burning through sanitizer at ~60ml/month (2 brew days × 30ml). You have ~7 months of supply. No need to stock up.

Usage this week:

  • Desk Organizer Set: +120g filament used, 3 parts printed
  • Muntons Brew Enhancer: fully consumed, batch complete ✓

This week’s project reminder:

  • Coffee table: still in progress. Birch ply: 2 sheets, need 1-2 more for base. Stain: 180ml remaining, likely sufficient for 2 coats on table + legs.

Total hobby spend this month: $0 (no purchases) | YTD: $214.87

3. Expiration Alerts

For materials with known shelf lives, OpenClaw sends a heads-up:

⚠️ Resin Check — Elegoo Standard Resin Opened: Feb 15, 2026 (179 days ago) Remaining: 580ml (~$17 value) Risk: Resin darkens and prints poorly after ~12 months opened

Options: (a) Use it for your next print — test with a small print first (b) Keep for non-critical prints only (c) Dispose and reorder

Want me to add “use old resin first” to your next print session reminder?

4. Cost-Per-Project Tracking

After finishing a project, you log the completion:

“OpenClaw, mark the Desk Organizer Set as complete”

OpenClaw tallies it up:

Desk Organizer Set — COMPLETE Duration: ~3 weeks Filament used: 847g Cost at material rates: ~$21.17 Notes: 3 modular parts, matte black, came out well

Added to project history. Your average cost per 3D print project: $18.40.

This data compounds. After a few months, you know what your hobby actually costs — not just what you spent at the hardware store, but per-project, per-category breakdowns.

5. Bulk Buy Decision Support

When you’re about to restock:

“I’m going to order more PLA. Should I get one roll or buy in bulk?”

Analysis: Your consumption rate for Polymaker PLA: ~45g/week At this rate, 1 roll (1000g) lasts ~22 weeks (5 months)

Bulk pricing (3+ rolls): ~$22/roll vs $24.99 single Savings on 3 rolls: ~$9

Recommendation: Buy 2 rolls. At your rate, that’s ~10 months of supply. 3 rolls would last 15 months — fine if you’re consistent, but the 4th roll risks degradation before you use it. Buy 2 now, reorder when you hit 200g remaining.

What You Need to Set It Up

  • OpenClaw with your preferred channel
  • A YAML inventory file — start with your top 10 most-used materials
  • Initial inventory count — takes 20-30 minutes to weigh and measure what you have
  • A weekly cron job — Saturday morning works well for maker schedules
  • Log as you go — every time you print, brew, or cut wood, note the material used

Limitations

This requires honest logging. The system is only as good as your data. If you print 200g and don’t log it, the usage rates will be wrong and the reorder alerts will be off.

Shelf life is approximate. Resin aging is affected by how well you sealed it, temperature, and light exposure. OpenClaw uses conservative estimates. Use your judgment on borderline cases.

Moisture damage is hard to detect in filament. PLA that looks fine can print with stringing and poor layer adhesion due to absorbed moisture. OpenClaw can’t detect this — but it can remind you to dry filament before a big print if you’ve had it sitting open.

Your inventory file will grow. This isn’t a set-it-and-forget-it system. You’ll add materials, retire old ones, and refine categories as your hobby evolves. That’s normal — budget 30 minutes a month for maintenance.

Some materials don’t play nice with YAML. Aerosol cans, partially used finishes,动手 DIY mixes — these are harder to quantify. Use estimates and note the uncertainty in the notes field.

The Bigger Picture

Most makers have two problems: they forget what they have, and they don’t know what they spend. The pile of filament in the corner isn’t organization — it’s a tax on your attention. The mysterious $300 hardware store visit three months ago isn’t tracked by anything.

OpenClaw makes your hobby inventory legible. You see what you have, what it’s worth, what’s at risk, and what you’ll need next. Over time, you stop buying duplicates, stop running out at bad moments, and start understanding the real cost of your projects.

The first time you start a weekend print without worrying about whether you have enough filament — because you already checked on Saturday and you’re good — you realize how much mental overhead this frees up.

Start with five materials. Add the rest as you go. Your future self will thank you when you’re not making a emergency Amazon order on a Sunday night.

Want to try this with OpenClaw?

OpenClaw is free and open source. Get started at openclaw.ai

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