I made this dope card holder, buy using old rc car parts and one set of old picatinny scope mount.
It works very well.
That packing where that card is holding, is made of the FORMcard, suberd items these for any kind of DIY jobs.
I am waiting on some special Neo magnets to make a new version but keep the card holder the same. I am hearing from some that have the system that down in South Texas heat the card holder can warp a bit, so I am looking at a new material as well.