Holder for aluminium diffuser purchased in Czech GME shop - AL509-1707-Black 1m. (Here - https://www.gme.cz/v/1503438/alu-175x7-1m-black-al-profil-pro-led-pasky)
To mount one diffuser you need to print 2 pieces - 1x downloaded model + its mirrored copy!
The author marked this model as their own original creation.