Nerf Meaker Mk18 Rotary Shell

I have no idea how this came to mind, but I we've got a revolving single-shot cylinder for my favorite printed Nerf platform, the Meaker Mk18.

Revision 25 Sep 2019
- Expanded barrel diameter to .51 for easier loading
- Added sealing ridges
- Expanded mounting slots to match R4
- Expanded base for better seal and rotation
- Added SolidWorks parts and .step files for your editing pleasure