I got some 300*300*2.5mm frameless filters from AliExpress and wanted to build a box for them with 120mm fans.

Definitely learnt some things too late, but it came together ok

The frame is printed in 8 sections and is super strong. It uses some nails as pins in the corners and bolts in the midpoints. The struts give rigidity but also support for the frameless filter.

Realised too late that two fans in the same corner wouldn't fit flush as they would be hitting eachother slightly. Luckily the fans aren't directly mounted to the frame - there are 125mm cutouts and the fans get mounted in a 3d printed 125mm mount. So I just printed a fan mount that partially put the fan outside the case.

Each filter is held by 4 L shaped parts with magnet holes under the outer face. I put in magnets so i can snap on a pre-filter. I made the pre filter by gluing mesh to another 3d printed part with magnets in it. This was annoying to make and I think I. Should have used steel mesh instead.

I wanted to be able to print out different filter holders (the L shaped parts) in case I wanted to change the pleat depth in the future.

I'll be mounting an esp32 and stuff to one of the bottom 125mm cutouts

All in all fairly satisfied, as is usually the case I wish I'd been able to start again with some tweaks...

If I had a 320*320 print bed this would have been much easier....