Warthog
Armadillo
random tracks
a lot of scrap plastic

CTAT (Cobra Tracked Amphibious Transport) Ironside
I took and lengthened the Warthog by about 4 inches and put it on longer tracks.
The original plan was just to make it an amphibious transport tank for hauling vehicles but once I got that done it dawned on me that I could make it a personnel carrier as well so I made a roof with a turret to go on it as well as making a tray of seats that could drop down in the cargo bay, Now it has multiple play uses. Plus it floats LOL