These are coil spring spacers to lift your 1997-2006 Wrangler or Cherokee front springs 2".
They have been tested to withstand 1650 psi printed with PLA @ 10% infill before deforming. Each puck should be able to support 12,900 lbs before deforming.
These have not been tested yet in the real world, I'll be installing them this weekend to test them out. Print and use at your own risk!
This was just an experiment to see if it could be done, turned out better than expected!
UPDATE 5/9/2014
These have been installed for two weeks now on a test Jeep and they're holding up perfectly. They've been down washboard dirt roads, bumpy trails and even a few street potholes. No signs of deformation, cracks, or other failures.

LONG TERM UPDATE 7/5/2014
Failure! I had a right rear puck collapse, so I reprinted one with 50% infill and it collapsed within days. After trying to figue out why one puck was collapsing, I drove the Jeep from work to home, then immediately put the FLiR camera on it and it dawned on me - the right rear puck was just a few inches away from the exhaust, which is plenty warm enough to allow the plastic to deform!

I've since bought a polyurethane spacer for the rears.

The front pucks are holding up excellently, even at 10% infill. Neither of the left rear pucks collapsed, but the springs did leave an imprint in the pucks, which was expected.

These pucks in a Cherokee should be A-OK since they are only used in the front. If you insist on running these in a Wrangler, I would suggest some sort of heat shield around the exaust whee it passes over the axle.