This is a simple plant light mount for the 45cm version of the ÅKERBÄR greenhouse to hold something like these lights: https://www.amazon.de/dp/B09WMCGJYX
You need 8 M3x6 screws or you just glue the pieces together. I used superglue and double sided tape to secure it in the greenhouse. It is a bit tricky to make this work but doable.
The author marked this model as their own original creation.