How to Scale Blueprints
I get asked this question all the time. To do it my way, you're gonna need to download paint.net. It's free, and I absolutely swear by it. You can download it here:
After you've installed paint.net. go download the stud grids that I have as a free download in the shop, they're under the "Helpful Things" category in the shop. Open that in paint.net, and your first part is finished!
Next, open whatever blueprints you're going to use in paint.net as well.
Now for the fun part. Go to Wikipedia or whatever you are using to find the specifications of the actual item you are trying to scale. Once you find those, head over to the following site:
This site allows you to scale dimensions down into Lego studs. Just input the actual dimensions on the left, on the top right type what scale you want it to be, and it does all the math for you. Input all the dimensions and make a note of them. Then, go back to paint.net and copy the blueprints. From there, click onto the second layer (labelled "blueprints") and paste your blueprint! From there, just expand or shrink the blueprints to fit your desired dimensions! Each square in the stud grid is a 1x1 Lego stud, so once you get the right dimensions just save it or export it to a .jpg or .png and you're good to go!