Here is an abstract nested design that ended up looking like a space family after printing and finishing. It comes apart and reminds me of an abstract mother, father and child. It also reminds me of those nested Russian dolls.
I used ReplicatorG to prepare the file, a MakerBot Replicator2 with the Replicator 2 slicing defaults and the following settings with white MakerBot PLA to do the printing:
Infill = 10%
Layer Height = 0.200
Shells = 1
Feedrate = 40
Travel Feed = 55
Temperature = 220
I used a raft with full support. It took 2 1/2 hours to print at 50 mm tall.