How to Design a 3d Printable Replica Gun

Hi all prop makers, today i'll show you how to make a 3d printable prop gun from a 2d image. 
In this instructable i'll make an anti material gun from fallout new vegas with moving parts.
Tools needed:
-123d design http://www.123dapp.com/design
- paper
- printer 
- 3d printer or 3d printing service like shapeways.com 
- pencil, rubber, ruler and calculator

I'm including my files of the anti material so you can just download and print 'em.

Step 1: 2d Designing the Prop

to make a 100% accurate prop gun you need to have 100% measures.
The first step is finding a reference image and printing it on paper.
Then you need to find the right scale between the real gun and your printed one, to do that you need to mesure a part you know the real dimensions. I measured the magazine on the paper and it was 2.2 cm, i knew that the real one was 10 cm so i did 10/2.2, the result was 4.5 so the printed gun on paper was 1:4,5.
Now the boring part begins.
You need to separate all the parts of the gun you want to be 3d printed so you need to redraw em in a 1:1 scale. 
After you did that you can transform your 2d designs in a 3d object.

Step 2: 3d Modeling the Parts

Now you need to create 2d sketches on 123d design by using the polyline tool.
After you did the sketch you need to extrude then faces using the extrude tool.
Now you need to bevel or fillet the edges to make them smooth.
You're done, just 3d print the models and glue the pieces with some super glue.