Gravitrax compatible basic tile

I got the idea for this part from Oostmeijer (see remix). Like him I've designed my part from scratch and I'm also probably using slightly different dimensions. The design was motivated by the following three goals:

1. Improved elevation system / stackable spacer (mechanical and optical)

2. Compatibility to Oostmeijer's inlays (I love them!)

3. Improved printability (ring is glued to the bottom after printing)

The correlating stackable spacers are based on Velando's design because they look amazing (see my other uploads).