Here is my take on upright stand for MBP (13" or 15"). It is for later models - 18mm thickness. Design allowed for 1.5mm felt on both sides. It is size that just fits Robox 3D printer. Note: Complete version is updated as v2. Original was 250mm (by mistake) while v2 is now 200mm - exactly what is easily printable by Robox.
Download from thingiverse