For complex curves (like a tank’s rounded turret or a plane's cowling), lightly dampen the back of the paper with a sponge. The fibers relax, allowing you to shape it over a bottle or dowel. Let it dry in shape before gluing.
Historically, GPM was strictly physical. However, due to demand (and the rising cost of international shipping), GPM now offers digital downloads via their official partner, (another Polish giant) and their own digital storefront. gpm paper model
Digital is harder . Commercial GPM kits have laser-cut parts for the tiny fiddly bits. If you print at home, you have to cut out every single wheel spoke and hatch hinge manually. For complex curves (like a tank’s rounded turret