Heapsofstitchin

Hi, first post how do you guys make patterns, I’ve used paper but i feel its a bit flimsy for making larger bag patterns. And the cereal boxes aren’t big enough to make the panel size I want, any recommendations for a sturdy card like material (preferably with guidelines on it) or any tips? Also, I have this notion I could draw my pattern on the computer, or iPad, and then print it out to scale. Is there a programme anybody uses to do this? Thanks, C