Tallhair - you made me do it.....I went back to the spreadsheet that I created when I started my project. My spreadsheet is much less involved than yours, but you've given me some ideas with this thread - thanks for starting this. My project is in teardown and some metal work at the moment. I need to add more estimations on future part requirements and cost estimates - I have not gone through in as much detail as needed. More importantly, I need to plan in more detail. I'm getting to that overwhelmed point right now and I think this will help......a little time planning will save a lot of time later. It's just hard to spend the time planning when there's so little of it!
There are several things I am tracking that I don't see on your tabs - but I'm sure you have more tabs in your spreadsheet than what we can see in this thread.
I am tracking tools purchased. I know they can be used for other projects but they are a cost for the one you are working on at the time. We buy a lot of tools if we plan to do it ourselves - and I know I'm not done! I had the basic hand tools before this project, as I never tackled this type of project before. So you find yourself buying air compressors and air tools, welders and C02 bottles, spot-weld cutters, special wrenches/pliers/sockets/vise grips, whatever. You can easily rack up a few grand in tools, if you don't have them to start with. Craigs list becomes your friend.
I am also tracking consumables that I purchase - grinding discs & sandpapers, cutting discs, wire wheels, paints&primers, tapes, welding supplies, degreasers, etc, etc.
You may have accounted for these categories - but I thought I would throw them in the mix.
Thanks.