This trackball tippler tilts thumb-operated trackballs by 45 degrees, resulting in much improved ergonomy as you do not need to twist your forearm. 

It fits the Renkforce RF-WM-501, Renkforce RF-4760558 and physically comparable trackballs found on Aliexpress, Ebay and elsewhere. 

You may either put the trackball loosely on the tippler or glue it to the tippler e.g. by double-sided tape. Access to the trackball's on/off switch and its USB wireless adapter receptable is possible through the tippler's backside cutout (see picture). 

Supports required (see picture).

As always I include the OpenSCAD source file for you to adapt and/or improve:

• Download and install OpenSCAD from https://www.openscad.org
• Launch OpenSCAD and open the enclosed OpenSCAD source file (/File/Open).
• Amend the parameters at the top of the file or even amend the code.
• Save your changes (/File/Save).
• Render the design (/Design/Render).
• Export the rendered design e.g. as a .stl file (/File/Export/Export as STL).
• Slice and print.

See my other designs at
https://www.thingiverse.com/thinger13/designs

History (TL;DR):
I owned the expensive but very ergonomic ("vertical", i.e. tilted 60 degrees) trackball (KENSINGTON PRO FIT M01480-M ERGO). Shortly after expiration of the warranty period it became defective. Unfortunately for, me Kensington refused to repair or replace it under goodwill. Opening it I found it a bit messy inside and not repairable. Given the short lifespan of the Kensington trackball I bought the Renkforce and ddesigned this trackball tippler to achieve essentially the same ergonomy.