Simple self draining microgreens trays. I like to have several different types of micro greens growing at a time and I've found using larger containers produces waste of both the greens and the growing media.

Simple instructions :

a) put a layer of media into the base (the part with drainage holes). We use coco-coir, but any media should be fine (cotton wool, paper towels etc).

b) soak the media and sow microgreens seeds on top of the media.

c) Spray the seeds with water. Cover with the lid and place in a warm location (a window sill is fine).

d) Check on the seeds daily and give them a little spray with water. 

e) Once the seeds have started to sprout remove the lid and sit the tray on it (it will catch any excess water and provide a small reservoir now).

f) Water daily, and harvest for salads/stir fries/garnish/snacks as needed.

Images shown are around 6 days in total growing Kale Red Russion Microgreen seeds.

If you are worried about growing in plastic, pick a food safe grade of plastic and consider sealing the print with a food safe spray/resin.