Maybe this helps somebody regarding magnetic numbers - this is how I do it.
1. Go to a graphics/sign store and buy a few feet of bulk, heavy duty, white magnetic vehicle sign material. It comes in a big roll so you buy it by the foot. Don't be tempted to get the stuff craft stores like Michaels sell. That stuff is too light weight and a lot more expensive. For example, in Edmonton I buy mine at High Speed Printing on 99th Street. In Saskatoon I bought mine at Crossman Graphic Supply. I think it cost me less than $12/ft.
2. Get creative on your computer and design some numbers using fonts that fit the regulations. Look in the Solo rules for exact specs as they might change. I used Illustrator but you could use Word, Photoshop, Paint, whatever.
3. Print the number(s) to page(s) and then cut them out.
4. Trace the number(s) on the magnetic sheet and cut them out.
5. To color the numbers go buy some spray paint and give it a coat or two. This also leaves a nice negative number effect on your garage floor should you omit newspaper or cardboard behind the numbers
I have also stuck a sheet of vinyl over the magnetic sheet prior to cutting out the numbers. Get the vinyl at the same place as the magnetic sheet. They have tons of colors. I've always wanted to make a set of numbers in plaid.
6. Go buy yourself/parents/gf/bf a new cookie sheet. Take the old cookie sheet from the cupboard because it is now your dedicated number holder to keep them nice and organized and flat. You want to keep them flat, not rolled up. Extra bonus points if you make cookies on the new cookie sheet.