Summary

Basically just a bunch of parts I modeled for a "water tank"
Hopefully it can float (untested)
I take no responsibility for any parts that are damaged using this model
Side note: You'll have to remodel the left and right motor tensioners because they don't have holes in them, and I might have a different sized motor than you
Here are the links for the belts and stuff:
https://www.amazon.com/gp/product/B00WXDAUQG/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B00CMIWP06/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B0747NYW6N/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
https://www.amazon.com/gp/product/B00FGYMFS0/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
And a list of the nuts and bolts and (optionally) O rings you need:
12x M8 screws/bolts (I'm too lazy to figure out the lengths - do it yourself! And if you're nice, maybe you'll tell everyone else what they are in the comments. )
12x M8 (preferrably locking) nuts
2x 8mm ID O rings
1x super huge O ring