I'm kicking around the idea of using Kickstarter to help me make a small run of a very simple kit (my first ever) over the summer, as an exercise for me to learn about the kit biz a bit. Right now, I've got early prototypes, BOMs and plans, and am struggling with estimating true costs at scale. In particular, my kit will use mason jars, which come in packs of 12, and 4-40 screws, which are best bought in packs of 100 or so. If the total number of kits is unknown, can one formulaically keep track of the number of 'packs' of parts will be required?
What is a good way of factoring in irregular quantities? Does anyone have any tips for keeping track of this in a spreadsheet (BOM)?