Gary mentioned how it would be worth having a record of how many hours it took to complete my project. This was enough to spur me on to add it to my spreadsheet. Most of the time I spend won't actually be on the spreadsheet. I'm not going to record, research time, documentation time, or correspondence time. I also won't include time that I pay someone else to spend (many of my steel cuts are done by my supplier for example). What will be included is fabrication time. I'm a relatively untrained fabricator. This means I'm less efficient than many who would undertake this project. Still, for someone who has done some carpentry, a little welding and a lot of experimentation this may be a reasonable estimate.
In the end I think it will be of major value to the OSE project to have records like those that I'm collecting. To have lots of data points on the costs (material, time, energy) of a Power Cube would really strengthen the case for OSE based businesses. I'm happy to collect data for my little project and hope to see data for other projects. Another person tracking their costs would help me understand when my costs are reasonable and when I'm slow or my materials are expensive. This may help me (or others) save major money/time.
Anyone can ask for access to my records in case they want to look more closely, or in case they want to use them as a template for tracking their own costs.