How can I make blueprints out of the downloaded files (.igs .SLDPRT) ?
I really want to make a paper AR-15 rifle but I need the measurements and the dimensions of the parts ( bolt, bolt carrier, hammer, etc..).
Btw I have the program called AutoCAD.
To what end?
Is this simply to print and hang on the wall, or will you be using the drawings to produce components?
I think learning is great. But making a drawing/blueprint is going to take some study time to dimension and annotate it correctly.
I'd start with smaller, simpler parts, and work your way up to more complex designs.
Another place to start is a search online for existing ar15 drawings. There are lots of them to choose from. You could either use one of these for your project, or you could use it as an aid while learning to create a drawing.
A large number of products and revisions exist under the title of AutoCAD. You may need to be more specific if you are looking for tutorials for a specific application.
The file formats you mentioned (iges, SLDPRT) are both 3D formats. Traditional "AutoCAD" is a 2D drafting program which may not work well with 3D data.
I'm really confused now. When you said "paper AR-15" I assumed you meant make paper drawings of the rifle. But you are planning to roll up paper to make a rifle out of paper?
There are dozens of better material choices. If paper is your thing, then sure, go for it. If you want to take a look at some other prop guns that have been built rather inexpensively (aside from the time required), check out some of the work by Volpin Props: http://www.volpinprops.com/portfolio/
Look specifically at some of his early work. Many of the supplies were sourced from dumpsters. He's since gotten more advanced with 3D printing, and silicone molds, but the same model building skills are used.
A great looking M4 Carbine model was recently uploaded. It looks to be mostly complete with the exception of springs for some reason. M4 Carbine
If you can open those parts in your CAD system, you'll be able to take any measurements you need. Of even print a drawing of parts at a 1:1 scale.