Stamp holder for OD 30mm with magnet in bottom

I design this holder for my resin printing stamps, they are 30.6mm in OD (outside diameter) and I think this can protect these stamps while make them more organized. I also made a space in the bottom which can fit magnet smaller than 20mmx10mmx2.5mm and I fix it with a 3M VHB tape. So it can stand more firmly and even can put on the wall (horizontal orientation)