Step 3: Make the circuit board
After I found the protoshield layout, I opened it and modified it in Eagle to what you see below. The second image is a close up of the PDF that will create the final board. There are a lot of great instructables about etching your own circuit board so i will not go over all the details here. The method that I like to use is describe beautifully in TechShopJim's instructable.
Step one: Print the PDF (found below) onto magazine paper, high gloss photo paper or a paper that is designed for PCB. Print using a laser printer. do not scale, it is layed out on a 8 1/2 by 11 piece of paper and it should print just fine with out modification
Step two: Cut out the design leaving a little bit of a boarder around the design.
Step three: Cut a piece of your copper clad that is a little bit larger then the design. the board can be cut by a bandsaw, a hack saw. But usually I will use a box cutter or Xacto knife by scoring it over and over again and then breaking it along the score line and cleaning up the edge with sand paper.
Step Four: clean the copper clad with an SOS scrub pad or steel wool until it shines, rinse it off and make sure not to touch the surface with your hands. Any grease on it will make it so the toner will not stick to the copper.
Step five: place the copper clad board onto a flat surface with the copper facing up, lay the cutout design toner side down onto the copper and tape it in place, put a paper towel over the whole thing and iron it on the the highest setting on your iron. NO STEAM! Place the iron directly on top, let the board heat up a bit before you move the iron and then take the edge of the iron and burnish the entire thing to make the toner stick to the copper. it should take about 3 min total. Remove iron and paper towel.
Step six: Soak the board in water to get the paper off. Don't be to rough while trying to take off the paper, the toner is very fragile and can easily scrape off. (If, for what ever reason it doesn't work, just take the SOS pad or steel wool to the board again and clean off any residual toner.)
Step six: Etch!
You can grab the PDF here. If you interested in the Eagle files, her is the .brd file and the .sch file