Summary

Motor mount for relocating the Y belt on ShapeOko outside the frame.

Instructions

Two options for motor mount, to relocate the belt outside the frame. This increases the usable area, and prevents the Z carriage colliding with bearings.

Clean out the 3mm holes so M3 bolts fit snugly. For the M5 holes, you can tap them with the same tool you used on aluminium MakerSlide, or clean them as per M3.
Refit the idler bearings to the outside, using spare holes near the bottom corners as pictured.

Mount A

Attach motor to mount with 2x M3 screws with washers
Use two M3 x 30mm screws through washers, plate, mount, into motor. These screws might not be easy to source; if it's a problem, use mount M below.
Use two M5 screws to secure the bottom.

Mount M

Attach motor to mount with 4x M3 screws with washers.
Attach mount to plate with 4x M5 screws.

My ShapeOko isn't running yet, so I haven't proven it under load. However, it should be more robust than simply mounting the motor out on spacers.

ShapeOko ext-belt motor mount