I wanted to post this in the hopes that it might help out some others who are looking to mount their Canon DSLR cameras to a 2" focuser and finding they just barely can't reach focus. Canon DSLR cameras have a 44mm focal flange, but nearly every t-ring adapter on the market uses their standard 55mm focal flange (adding 11mm of material). That 11mm is crucial if you're hooking up a camera lens that uses a t-ring mount, but it's unnecessary when sliding the adapter into a 2" focuser tube. I need more than 11mm for my GSO dob, so I'll either move up the mirror or get a coma corrector. For others, 11mm might mean a lot.
This is 3D printed in solid PETG and allows the camera's lens flange to sit directly on the focuser tube. It could be sanded/painted or printed in finer detail so the layers aren't so apparent, but I'm fine with function over form for things like this. I saw a few similar designs on Thingiverse, but they all seem to have comments about not fitting well. Mine fits very snug in both of my EOS cameras. I can upload the file later if anyone is interested. I may go the mirrorless route myself and redesign this for EF-M. The 18mm focal flange distance and 11mm this provides might be sufficient... we'll see. Forgive the ash on my scope in the photos. It's still everywhere in my garage.
Empty 2" GSO focuser tube
Focuser tube with standard t-ring adapter (notice 11mm flange between tube and bayonet)
Focuser tube with printed adapter (only the Canon EF bayonet sticking out)
Camera mounted on telescope with standard t-ring adapter
Camera mounted on telescope with printed adapter
Camera with standard t-ring adapter
Camera with printed adapter