Well, I have been experimenting with how to build Foam Risers out of pink extruted foam, that look and act like the Woodland Senics Risers. After a few attempts with various tools and techniques, I have come up with this guide.
Calculator (If you are not good with math skills)
Long piece strait piece of metal or wood (preferably about 1/2" thick) and longer then the side of foam you are cutting.
Sharpie or some form of making device.
A SHARP Brake Away Knife.
And a 4x8 Sheet of Pink or blue foam about 1.5" (N-scale) or 2"(HO I think)
First step figure out your grade you wish to use. I use a 3.1% grade which came out to be a rise of 3 inchs in 8ft of running. Which works out great for cutting the foam. I decided to use the Short side or the 4 foot long side of the foam board. Which means that in one cut I will start at zero inchs which will be the starting elevation. The other side will be at 1.5 inchs up from the bottom which will be the ending elevation.
Second step. Check for a strait cut at the edge of the board. If you don't have a strait edge follow the next few steps in cutting to cut a strait and square line with the side of the foam.
Next Step. Mark your elevations at the start and end of your run. So one side will be marked with the Starting Elevation. Which will be Zero. and the Other side of the foam marked with the ending elevation.
Next Step. Line up your board or strait edge that is longer then the side of foam, on the two marks. For my use I used a 6ft long board that I cut to about 1/2" x 3/4" on a table saw. I also found out that if I used a few nails pushed into the foam on the back side of the board to hold it in place, it wouldn't move much. Like in the picture:
Next Step. Get your extendable Breakaway knife that is SHARP. Make sure your knife is sharp, you get much cleaner cuts. Press down on the board to insure it dosen't move to much. Take your knife extend it out just enough to score the foam on the first pass. Run your knife along your strait edge at about a 45degree angle to the foam. While keeping your Knife strait up and down.
Just keep repeating, running you knife along the strait edge making slightly deeper cuts on each pass. You only need to make about 1/8" or so deeper cuts at each pass. Until you cut threw the foam.
Next Step. Get the Tape messure and your newly created foam riser. On one side of the riser mark where every inch mark is. On the opposite side mark where every half inch mark is. So all the marks are about 1 inch apart from each other. And not on the top or bottom.
Next Step. Get the Hack saw. Yes the Hack saw. And this is the messy part of the whole process. Cut a 1/4" wedge out of the riser about 2/3 of the way threw on all the marks. I found that the Hack Saw is the fastest way to cut the 1/4" chunks out of the riser to make it flexible. I tried a foam cutter but it was way to slow for me.