Which type of blade would be better to use for paper model building?



Top? Or bottom? Thanks.

You really want to stick with a blade that is cheap and easily replaced. Although it's just paper blades do tend to become dull fairly quickly. The problem with the two you've shown is that they don't have a ton of easy "resets" (snapping off the blade) before you have to replace the whole thing.

In my humble opinion the best blade type for your money is the dirt cheap generic Exacto cutting knife. If you can afford a metal bodied one all the better but the key here is that the blades are very inexpensive. One other thing to look out for is the amount of "play" the blade itself has in the body. What you don't want is a blade that wiggles around too much :