Mini Worm Composter

OX3D_Parts Mini Worm Composter – Compact Vermicomposting for Home

The OX3D_Parts Mini Worm Composter is a functional, stackable system for efficient composting of small amounts of kitchen waste – ideal for apartments, balconies, offices, or small households.
Developed, designed, and tested by OX3D Parts, specially optimized for FDM 3D printing.

⭐ Features
    •    Compact & space-saving – Base dimensions 200×200 mm, suitable for common 3D printers like the Bambu Lab P1S.
    •    Well-designed ventilation concept – Side air slots for oxygen exchange without drafts.
    •    Drainage bottom – 3 mm drainage openings for excess moisture.
    •    Stable construction – Optimized for PETG, 3 perimeters, 0.16 mm layer height.
    •    Easy to print – No support structures needed.

🪱 Instructions: Setting up & operating a worm composter

1️⃣ Preparation

Materials
    •    Worm composter (e.g., multi-tier, like the one you built)
    •    500–1000 compost worms (Eisenia fetida / Eisenia andrei)
    •    Moist cardboard, egg cartons, or newspaper (unprinted)
    •    Some finished compost or garden soil (optional)
    •    Spray bottle with water
    •    Kitchen waste (plant-based)

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2️⃣ Setting up the worm composter

Step 1 – Create the base layer (Moist, but not wet)

Place a 3–5 cm layer at the bottom of the first tier:
    •    moist cardboard
    •    shredded egg cartons
    •    some unprinted newspaper

👉 This is the initial moisture layer and provides habitat for microorganisms.

Moisture test
    •    Squeeze a piece:
→ Water drips = too wet
→ Stays dry = too little
→ It should feel like a wrung-out sponge.

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Step 2 – Introduce the worms

Place the worms on the prepared layer.
Cover them lightly with moist cardboard.

⚠️ No light → worms will then burrow in on their own.

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Step 3 – First feeding

Feed very little on the first day:
    •    1–2 handfuls of vegetable scraps
    •    cut as small as possible
    •    mix with some cardboard (brown material)

Important in the initial phase:
➡️ Less is more!

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3️⃣ Regular operation

🥕 What can go in (green / nitrogen-rich)?
    •    Vegetable peels
    •    Fruit (sparingly with citrus!)
    •    Coffee grounds + filter
    •    Tea bags (without plastic)
    •    Ground eggshells
    •    Plant trimmings
    •    Potato peels cooked/uncooked
    •    Rice and pasta in very small amounts, preferably dry

🍂 What can go in (brown / carbon-rich)?
    •    Cardboard
    •    Egg cartons
    •    Kitchen paper
    •    Unprinted newspaper
    •    Straw
    •    Leaves

⚖️ Rule:
1 part green → 2 parts brown
This keeps it odorless, loose, and airy.

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🚫 What must NOT go in?
    •    Meat, fish
    •    Dairy products
    •    Oil, grease
    •    Large quantities of bread (mold!)
    •    Large quantities of citrus fruits
    •    Large quantities of onions/garlic
    •    Animal feces (except rabbit or horse, well-rotted)

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4️⃣ Moisture & Temperature

💧 Moisture
    •    Optimal: 65–75 %
    •    Test: Material like a wrung-out sponge
    •    Too wet → add cardboard
    •    Too dry → spray

🌡️ Temperature
    •    Optimal: 15–25 °C
    •    Below 10°C → slower
    •    Above 30°C → dangerous, place box in a cool spot

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5️⃣ Using worm tea (leachate)

If your composter has a drain:
    1.    Drain every 3–7 days
    2.    Dilute 1:10 with water
    3.    Perfect as a natural fertilizer for plants

IMPORTANT:
If a lot of worm tea is produced → composter is too wet → mix in more cardboard.

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6️⃣ Using harvested worm humus

After 8–12 weeks, the bottom tier is ready.

Features:
    •    Dark, crumbly
    •    Earthy smell
    •    Almost no visible waste

Usage:
    •    Mix with soil for beds
    •    Improve potting soil
    •    As a compost boost for tomatoes, pumpkins, chilies, etc.

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7️⃣ Typical Problems & Solutions

Odor

➡️ Too wet or too much kitchen waste
→ Add more cardboard, mix, leave open briefly

Fruit flies

➡️ Waste not covered
→ Always cover with cardboard/soil
→ Place yellow sticky traps nearby

Worms escaping

➡️ Too acidic (too much fruit), too hot, too wet
→ Cardboard, lime (eggshells), aerate

Mold

➡️ This is normal!
→ Simply mix it in
→ More worms & aerate

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8️⃣ Feeding rhythm
    •    About 1–2 times per week
    •    Amount: as much as the worms can process in a week:
approx. 25–50 % of their own weight per day

For 500 worms (approx. 250 g):
→ 125–250 g of waste per day
→ Max. 1 liter of waste per week

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🪱 Summary

👉 Initial setup: moist cardboard + worms + little food
👉 Continuous operation: feed 1–2 times per week, check moisture
👉 2:1 ratio: cardboard > kitchen waste
👉 Drain & use worm tea
👉 Fill tiers gradually
👉 Harvest humus after 8–12 weeks