IKEA Milsbo cabinet - grow station

I designed new corner pieces for the IKEA Milsbo cabinet so that 8 mm aluminum rods could be attached all around. Cup holders for 300 ml cups can be hung on the aluminum rods. There are also additional elements for attaching shelves made of aluminum rods. 
The corner connectors are attached to the original screw points on the Milsbo and also serve to secure the glass panes.

Plastic cups with a volume of 300 ml fit into the holders. 

What else you need:
Long side: 8 mm aluminum tube, 60.5 cm long
Short side: 8 mm aluminum tube, 27.5 cm long
For the self insert: 8 mm aluminum tube, 63 cm long

The preferred material is PETG.