Here are two variations of a melted LEGO brick in standard size. I've also included one of the designs in twice standard size (DUPLO). These should be printed with support at the angles shown in the SLA files. This way the bricks will be printed parallel to the build plate and will look the best.
Update 11/23/14: I've added improved versions of these bricks with slightly thicker bases that are easier to print and finish.
Update 12/9/14: The V2 file names now correctly match the files.
Designed in Fusion 360, sliced in Simplify3D, printed on a MakerBot Replicator2 with 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