The conner brackets were drawn by first drawing 45-45-90 triangels whose legs are 20mm long. The triangle was then extruded 20 mm. 

We then printed 4 brackets and used epoxy glue them into the corners. 
After inspecting the difference that they made, we printed 4 more. 

The brackets improved the rigidity of the enclosure. 

Use as many brackets as you feel like you need.

The handle was drawn by drawing a 2d rectangle. Then the rectangle was offset by 20mm. Next lines were drawn to connect the inner rectangle to the offset. Then rectangles that were 20mm x 1mm were drawn on the inside portion of the "U" area.  This was to increase handle's surface area touching the enclosure.

This "U" shape and the 20mm x 1mm rectangles were then extruded 20mm and given a fillet.

Lastly, holes that are 110mm apart were drilled through the sides, and the handles were bolted on using the 6-32 scews and washers.