I did some numbers quite successfully not to long ago.
In Corel Draw, I have a script that rounds the corners of a polygon, so I took some block numbers and rounded the corners to 5/8" (for a
1/2" router bit), and printed them on a laser printer. I then ironed the paper onto a scrap sheet of MDF (laser printers use heat activated ink! A trick I learned from this forum), and using a skill saw and a router, I carefully crafted that into some nice templates. I then taped those to the back of some glued up cedar (so the numbers appeared backwards...), and using a pin router, routed the front. I then used a carving chisel to add texture to the background.I thought I could get an inverse form easily by using plaster of paris, but that didn't work (at least on my first attempt). One of these days I'll get some free time, and I'll try another method. Here's some pics:
John