Ultimaker 2 - Improved slider block

This design is largely based on the original slider block of Ultimaker 2 (first edition September 2013).

What's different or better?
- This is not a pure 1:1 copy, but a variant newly created. with the essential features and dimensions from the original!
- This design is not optimized for injection molding, but for 3D-Print.
- All snap locks can be opened more easily, so that maintenance work can be performed easily and reliably.
- When you create a small supply as a precaution, you need