A drawback of paper modeling is that paper doesn't form compound curves readily. But it will form them to a limited degree. Some guys use radical techniques like wetting or even pulping and forming the paper, but that tends to mess up pre-printed coloring so is mainly useful if you're going to paint the model later. The one method that works well on pre-printed models is embossing.
I used a dried-up ball point pen on a soft surface (paper towel folded x4) to prep the Travel Air front cowling ring. basically I made a circular squiggle down the middle of the curved strip part. This simultaneously curled it lengthwise, so that when finished it formed almost a perfect ring, and imparted a little curvature across the width of the strip. Not enough to give a really scale appearance but better than just a flat cone.
Finished cowl with engine cylinders. The cylinders aren't very well made as so little of them will be seen. If this were a plastic build it would be easier to get a proper shaped cowling and I'd use either an aftermarket engine or scavenge from a kit (although 1/72 Wright J-6-9, a/k/a R-975, engines aren't easy to find in either form).
Meanwhile the fuselage comes together, or I should say the first fuselage. I printed and prepped two fuselages because it is such a difficult part that the odds of my first try being good enough are poor. That's the great thing about self-printed paper models; unlimited do-overs. I used the embossing technique to apply a bit of airfoil shape to the tail fin. The clamping tweezers are among my most useful paper modeling tools.
August
A good model is any model you can walk away from.
