Yet Another Wall Spool Holder

After having a shelf come down from too much weight (printed in PLA), decided to upgrade the shelf brackets.

__NOTE: Designed to work with 1/2" PVC pipe.__ Will probably make a few mods for other sizes soon.

Did remix of [this one](https://www.thingiverse.com/thing:2930922) and took inspiration from [this one](https://www.thingiverse.com/thing:3104484). Especially like the 'triangular holes' which actually add strength due to increasing the wall count in the supports, since infill generally isn't very strong.