D3P Riser-Compatible External Spool Holder

Despite a few quirks (at least in my print / build), I've been pretty happy with DARREN3DPRINT's modular riser for QiDi Q2. But me being me, I can't help but come up with use cases that I want to do something about, so I "remixed" (basically, rebuilt from scratch) the external spool holders accessory for some additional flexibility, at least until my QiDi Box arrives, and made sure I had permission to publish from D3P.

This D3P Riser-Compatible External Spool Holder has been modified from the original in the following ways:

- Additional notch allows orienting so the spool sits below, or above, the riser.
- Integrated a QiDi-compatible spool holder mount, so the stock spool post or others based on that mount, can be used.
- Includes a mount plate with the OG D3P threaded post so existing D3P spool holders still work.
- Includes a plug to keep the spool mount / plate in place in either orientation.
- Just a bit longer overall for some additional leverage on the fitting surfaces in the