Summary

A small box for this power supply: http://www.banggood.com/5V-1A-AC-DC-Adjustable-Power-Supply-Step-Down-Module-Bare-Board-p-980522.html

Or any other gadget that fits the inner size of this box:
Length: 52 mm
Width: 25 mm
Height: 15 mm + 2 mm below the stand-offs in the bottom

Outer size with lid on:
Length: 57 mm
Width: 30 mm
Height: 22 mm

I am using this power supply for some different Arduino boards. So it is never under any big load. It might be warmer and need some ventilation holes if you pull more power from it.

You can get the model for Autodesk 360 Fusion here:
http://a360.co/1R2PJwN