I've hacked several toy tanks but always wanted to me able to make my own tank treads for robotics projects.
I played around with several different models but couldn't find much to go on other than picture and diagrams.
I've built in some play and made sure the links should print on a makerbot without any problems (minimum overhang).
This design is untested
Plate 1 = 4 drive sprockets
Plate 2 = 24 Treads links
Print out as many of the sprockets/links as you need and assemble the tracks by using 1mm thick pins (coarse wire)