Step 3: Make the grow beds
Cut the plastic colander into fourths. Glue 1/4 of it over each of the two holes in the grow beds to keep the gravel from flowing out the hole. You don't need the rest of the colander.
Support the back of the drain funnel with zip ties from the corners of the grow beds.
Wash the pea gravel with water and put it in the grow beds. Then rinse it more until the water coming out is clear.