Magnetics are a lot easier and less expensive for this club than some where the numbers are assigned for each event without a choice.
A reminder that I do own a vinyl cutting machine and have magnetic sheet as well as heavy duty static cling film backing for the ferrously challenged cars and offer special club pricing.
There was an instance this weekend where a car had paper #s, but their handmade paper class lettering could not be read from more than a couple feet away. If you are doing your own markings, review the minimum size requirements, including stroke (the width of the thinnest part) and exceed them if possible. (I personally think the minimum size is too small in most cases, I'd recommend #'s at least 10" tall with 2" minimum stroke, and class letters at least 6" tall with 1-1/2" stroke) Check that they can be read by walking a significant distance away (like the distance from the bus to the start line Sun) and see if you can read them easily at a glance. If you need assistance with doing your own just ask, pm, email me, I'll be glad to help, no charge!