Well I have a fav tank and that is the Lemanmuss. When I was playing 40k I have a bunch of them for both my Orks, and my IG armies. So when I moved to 15mm this is the tank I wanted to use. The problem was no one made it in 15mm, and that would be a copy right issue. But one day I found a web site that had the plans for most 40k vehicles. I took a look at them and though I could scale it down and make some for 15mm. I printed it out using the % print option and sure enough I was able to make a Lemanmuss in 15mm. Here are some photos of my first one. Now this tank is a bit big and will need to scale it down a bit more, but it was the first.
Here you see the tank with some minis, so you get a feel for the size. And yes this tank is made out of paper, and PVA glue. I did you card stock (thick paper) and I printed it out on my regular printer. And yes the main gun barrel is paper. I rolled the card stock around a drill bit and glued it in place.