Small carpenter's square (to make sure joints are perpendicular)

*Either*
a router plane with a 1/8 square-bottomed groove bit
*or*
A router table with 1/8 flat bottom cylindrical bit (end cutting)
(to make straight shallow grooves in the acrylic)

Chamois (to wipe down the plastic dust after machining before assembly)

Optional: Pad sander (I did it by hand, but power assistance would be rather useful here)

Sanding block

Patience