The trays are made using a screen kit available at the hardware store.  The mesh material is made of stainless steel, which can be easily cleaned and has a long service life. 

I obtained the stainless steel locally at: TWP Inc.,
2831 Tenth Street, Berkeley, CA 94710 USA.

Phone 800-227-1570   510-548-4434

Their website is: http://www.twpinc.com/twp/jsp/address.jsp

When transferring the sprouts to the growing cabinet, pour the sprouts into a big bowl (not shown) and clean off as many seed husks from the top of the water as possible. Carefully use a fork to wade through the bowl of sprouts lifting off sprouts in small clumps. 

I place the empty screen into a tray of water and float the sprouts over the screen - distributing them gently over the screen. 

Once the sprouts are on the screen do not over handle them, as they may break. Try to keep an even layer of about 1/2" of sprouts across the screen. In a few days the leaf portion of the sprout will be vibrant green, as the roots grow through the screens.

After harvesting the sprouts you can easily clean the screen by turning it over and striking the frame gently on the floor. Roots that stick to the screen can be removed with your fingers, or a spatula. The screens can be cleaned with a small brush to get them ready for your next crop.