This end-cap replaces the stock buffertube end-cap when medium sized batteries are used with the ARP. The stock end-cap doesn't allow medium sized batteries to fit entirely inside the buffertube without wires sticking out and this one does. It is slim enough to still allow the stock to fit while giving lots of space for parts of batteries and wires that don't fit entirely into the buffertube.

I designed it to be printed with line widths of 0.8mm, so make sure to set the line widths to either 0.4mm or 0.8mm

https://www.thingiverse.com/thing:4915732