This is a modified version of the original that has been broken up to include a base plate to attach to the aluminum stock extension. Included are two sized extensions to increase or mix/match to size. The original rubber butt plate can be attached allowing you to use either a ridgid fillament or TPU as you wish. A end but plate is included if you need to print a new one.
The base plate is attached with M5 bolts and the exentensions are attached with M3 bolts (length is dependent on the extensions you choose) and M3 nuts. The original butt plate is attached using the existing bolts.
NOTE: The modifications were done in PrusaSlicer and cannot be exported as individual STL's doe to the negative space adds. I will update if I can get properly do this into individual STLs.
The author remixed this model.

Splits the original into parts that can be mix and matched to make various extension lengths. This also allows you to use PLA or another more ridge material then attach the original rubber stock end.