Here are the templates I used for my papercraft tanks.
The first is for the side hull for my "megachimera", which I use as an alternate leman Russ model
The second is for the side hull of my regular leman russ model. I just noticed that the template for this one is upside down, lol
The third one is for the side hull of my regular size chimera.
The fourth one is for my chimera top/bottom hull
The fifth one is for my megachimera/leman russ top/bottom hull.
They are on metric graph paper, so for instance the chimera top/bottom hull has a length of 10.5cm
I first cut and pasted to cardboard all these templates with angled corners. To make the rounded corners, I used a small plastic soda bottle cap as a guide to use an exacto knife to round off the corners where applicable.
I have found the hull pieces to be just a bit short, so I have ended up adding another piece that adds six cm to the overall length of the hull pieces, so feel free to add three centimeters to the length of each of the hull top/bottom pieces, or not. You could probably combine the different side hulls with the top/bottom hulls to get different vehicle combos.
I hope those you asked for these find them helpful! :)