I couldn't resist designing a plate for LEGO bricks that had more than just 90 degree angles. There's a lot of flexibility in things you can build using this plate. I've included two examples here.
Note: The photo of the bottom was printed directly on the build plate. The other version was printed with a raft. I'm now able to successfully print this directly on the build plate.
Designed in Fusion 360, sliced in Simplify3D, printed on a MakerBot Replicator2 with side panels and Elmer's Craft Bond glue stick on a glass build plate with PushPlastic filament and the following settings:
Infill = 20%
Layer height = 0.2
No. shells = 4
Feedrate = 40
Travel Feed = 55
Temperature = 220C