The dev kit has to have a physical base, and something that can protect the fragile boards and wiring within, even when team members are on the go. I made a box design in Fusion360 and cut plywood and pine with a hand-saw...

Then wood glue and rubber bands...

And then a fresh coat of paint..

Not pictured, nailed them together for extra strength and to stand up to the stresses of general life like being thrown in a backpack or dropped.

A few mistakes here and there, mostly in trying to nail such thin plywood, where nails would veer off and rip out the sides instead of going in straight and clean. And my hand sawn cuts weren't perfect, but nothing that couldn't be cleaned up with a microplane and some sandpaper. 

If I could've done these on a tablesaw, I would've painted the plywood before cutting, but I'd noticed before that hand sawing plywood sometimes strips the paint away at the cut, so I opted to paint after assembly.

Useful for this stage was Tom Sachs' Love Letter to Plywood, and having basic hand tools and a ruler.