Looking at what I've tried to construct, I've found some airplanes a little harder to construct, either in successful (or unsuccessful) attempts, or just by looking at the aircraft or visualising the model. I'd like to know what you find most difficult. Jaguar- My first model (photo uploaded on the old Card Models gallery before it vanished) was quite sad. I designed a better model (with a modification in a clone) in Blender, and found that despite the sharp, square corners, it's not that simple, especially when there are as many curved faces. My later model had some full wings as well. If I could give it a number, the difficulty level would be 50%. MiG-29- My first (and only till date) model (I don't recollect uploading the photo here, it was there on the old gallery) was quite easy to construct. It was totally hand-made, using drawing instruments, and I stuck coloured paper on hard card. The wings and tail fins were flat, and the armaments very basic and flat. What I did was quite easy, but the engines were flat. That model had a difficulty level of 30%, but if done more carefully, it would be 45%. Su-27 Flanker- Another hand-made model, but going a step ahead with the rear engines, and changed the wings (and what holds it). These wings were flat again, making them sturdy, and it's my most robust model till date, but painted in acrylic paint, it's a little ugly. Not to mention, the canopy looks ugly. With some guesswork, it came together. That part would give it a 74%. Su-30MKI- Made using Metaseq and Pepakura. This was done using the same dimensions as the hand-made Flanker, and modified slightly to make full wings. It was my best looking model (till the Jaguar IS) but it's very unstable, and folding it would be tough, unless you constructed the model yourself or have a reference. Giving it 77%, because construction is tougher than design. Both models can be a lot easier to design and construct if done better. Airbus, Boeing 707/737/747/757/767/777- I've tried to design a Boeing 707, and while building the fuselage looks ridiculously easy, making cuts for wings and fins is quite a tough ask. I have now found an easier way of marking the fin/wing areas using textures, so it's a lot easier. My first design wasn't much good, but taking what I've learnt in the last model ahead, I can make one better. I even have a solution for the wing-to-fuselage phase. Now I give it a 45%. Tristar/DC-10/Boeing 727/717/Caravelle/Tu-104- More difficult because of the location of the engines. Still trying to visualise. Giving it a difficulty level of 70% for visualisation. MiG-23/MiG-27/Su-24/F-14/Tornado/Lancer- Easy to design, with almost nothing to it. Then there are swing wings. If you're new to it, the design gets a 82%, even if you're just visualising. Concorde/Tu-144- Easy. Barely 29%. Oh well, making the droop-snout gives it a 35% in design. Civilian propeller airliners/A-1 Skyraider- Very difficult even in design. Full wings and the engines (with props) make them tough. They get a 60%. I've thought of a Lockheed Constellation, and the tail assembly takes it to 77%. Attack jets- They look easy, especially the A-3, A-4, A-5 and especially the A-6. They get anywhere between 35% to 40%. The A-7 is a little more difficult, getting a 47% for that intake/fuselage assembly. Jump Jet- Difficult. Really. Not rated because it's way back in the pipeline. Northrop YA-9- Easy, but reference is difficult to find. Else you'd make it. No comment. Thunderbolt- A personal favourite, and my second card model (first without livery issues- My F-16 was done in Blue Angels colours), made flat. The model is very easy to visualise, getting 24%. F-4 Phantom- Modelling in 3ds Max, I've made one quite easily. Barely 40% to design. F-16 Falcon- Really difficult even in design. Same problem as in A-7 Corsair, but magnified, to a rating of 70%. I could go on, but I'm keeping it down to just those models I've worked on in card modelling or 3-D graphics. I'd like to know what models you find difficult (or otherwise) and how much. All of these models, we'd all agree, would be a lot more difficult if we used transparent and detailed cockpits.