Neva Brick Spool Mount

Neva comes without a spool holder and you are expected to print one yourself. I used the [Dagoma-designed spool holder](https://www.thingiverse.com/thing:2365668) to hold a spool at the top of my Neva. Dagoma's design works really well but there were a few annoying things that I decided to solve by making my own spool holder from scratch. Here are the goals that I pursued:

- **Neva-tailored shape** (spool holder should maximally make use of Neva's dimensions);
- **Secure installation** (