I've been racking up a bunch of shop tips that I've wanted to post for a long while, so I'm going to begin chipping away at it!
I have searched for a good material for pattern making for a long time. I found "for sale" signs to be good plastic that lasts forever and is easy to cut and manipulate. Plus, it's thin enough to mark a fine point through, unlike mdf or masonite etc. I've used poster board for years and it degrades seemingly instantly!
I found that high impact polystyrene that you can buy in 4'X8' sheets from Amazon is the same stuff as the for sale signs but cheaper and bigger. You can cut it easily with scissors and even use spokeshaves on the edges to get refined curves. I'll show some of the benefits of it's flexibility soon. You can snap it by hard creasing it, so some care in handling is in order, but I've found it to be super durable.
You can write on it with sharpie markers and erase the marker with denatured alcohol if needed
I'm in the process of remaking my vital patterns in the material. If you want to check it out, go buy a for sale sign and give it a look.