For all flat parts, you basically need nothing else then a flat plate like a sheet of steel. I find it very convenient to use a glass plate. First: it's perfectly flat and absolutely airtight, but second: you'll have the possibility of a visual control of the resin flow at the bottom side of your laminate. But the point is: investment in tooling is very low for flat parts. For double curved parts, it get's slightly more complicated. But since most curved parts on a aircraft will probably have something to do with aerodynamics, I would rather spent some more time on getting the right geometry. And it does not really matter so much whether you spend your time on sanding and filling a tooling surface or on working on actual part. O, but adding filler on the actual part also increases the weight.... But as soon as you have the tooling finished, making the actual part is peanuts!
It seems to me all of you are more or less building the same aircraft. Why not use one finished aircraft and use that as a master mould for getting a complete set of tooling? And have that tooling circulate among all the builders. There might even be some business in doing that! That will probably safe all of you a lot of time! You will be able to infuse a complete wing structure in a couple of hours, rather than spending weeks shaping your wing. Or to take it to the next level, would the regulations for kit-aircraft allow complex parts being build by one company which supplies them to all the home builders who'll perform the assembly? In that case, I'll build (and vacuum infuse!) the parts for you!