Make your own earthworm farm! Remember to keep the box in shade / indoors or cover if exposed to sun at any time of the day.
Secondly, take note of air holes – earthworms breath oxygen so add as many as you can (you can cover with a mesh to help keep other bugs out).
Lastly the drainage holes between the levels allow the water released from the food materials being broken down to drain away). If you have your box indoors, then a tap is great to empty the leachate (the water that collects at the bottom of the system) which you can add back to the box or dilute 1:100 and feed plants (not your veggies, there are still pathogens in this liquid). If you have the box outside this can drain directly to the soil.
Lastly, when filling your box, add a layer of browns (dry leaves/grass, brown cardboard) to your layer of greens (kitchen scraps, green plant material) to keep the balance in the system. Too much greens will make the box too hot and will smell – if this happens add more browns. Keep the contents moist, not wet/ dry as the moist environment allows the earthworms to keep moist skin and this is how they breath.
Add a handfull of sand / coffee grinds / rock dust as teh earthworms use this to break down their food.