Modular Hydroponics Tower Netcup Seeding tray - Greatly improved

This is an improvement to my previous net cup holder.   It's designed to hold the net cups that you can print for the modular hydroponics tower that is very popular.  

This version has two main design improvements.   First, I removed the legs and added cross supports.   The supports prevent the tray from sagging under the weight of the net cups when they are loaded with rockwool or your choice of seeding medium.   Second, I added a plate on the side with holes that allow  you to join two units together.   By joining two units, the trays will fit well on top of a standard 10/20 seed tray, blocking any light from entering the tray and thereby preventing algae growth.

I also added supports around the holes to hold the net cups at the correct height, so they sit just a few millimeters above the bottom of the 10/20 tray.  

The whole point of this tray is so that you can do your seeding directly in the net cups.  This avoids having to transfer the young plants and risk damaging them or stressing them out.  simply lift them from the tray and twist them into the tower garden.  

Note that you need to place this on the tray with the supports facing upwards.  When you place the net cups in the tray, they should sit just above the bottom of the 10/20 tray.

I recommend printing this either in black, or another dark colour to prevent light from getting through.  If you use white, you will get algae growth over time.