Yes, you can make it yourself...it will just be a little time consuming. I always bought it because the laminations in bingham's riser blocks are so thin...i dont think i could...or would want to try to make them that thin.
Here are the steps to making it yourself, lets say this is for a 2" x 4" x 22" block
1. Get a block/board of hard maple...or birch
2. Square the block and run it through the drum sander to true it up.
3. Slice a thin strip (i.e. 1/16" x 4" x 22") off on your bandsaw..(thickness is up to you really)...for your first time just try 1/8
4. True the block on the drum sander
5. Repeat steps 3&4 until you get enough laminations to make your riser
6. If you want to make it camo, get some Lockwoods's dye and dye the individual laminaitons alternations of grey, green, brown or whatever you want). Let this dry!!!
7. Clean laminations and glue up with Smooth on or some other epoxy which you prefer.
8. Unclamp it and clean up the edges and you have a riser block
9. Take a picture and show us the results please
best of luck