Reel Adaptors for 26mm spool holder - 45mm - 76mm + parameterized model

NOTE: On 23 Nov 2020, I updated the design and the associated files from v2 to v3, to add a small reinforcement rib to the flexible tabs. This makes the tabs much less likely to snap when flexed. My apologies for those of you who - like me - may have had breakage with the v2 files.

This is the 2nd generation of my thing:3783495.
The design is simpler, robust, and verified on my Ender 3. The flexible tabs bend slightly to hold the inside of the reel, so these can be printed in rigid material, like PLA, PETG or ABS.
Again, the centers are sized to fit 26mm Spool Holders.
e.g.: thing:3789632, thing:3821380, and thing:3789523

I have included the Fusion 360 file from which these particular .stl files were saved, so that you can "bake your own." Hopefully, the instructions below will make sense and will work for you.

If you need to make an adaptor that will fit a hole smaller than 45mm, you will need to scale a larger one down, or modify the model.

CAUTION: I am finding that some filament manufacturers are letting a small amount of the filament stick out through the inside of the hub, very close to one side. You may find that this makes the hole smaller on one side of the reel than on the other side. Be sure to measure both sides when deciding which size of insert to print...