We have been doing some significant design work, mainly on how the research and parts system interacts.
Daffyflyer has started on the daunting task of modelling engine blocks, top ends, headers, intakes, cylinders etc (As a bit of a change from the buildings). He calculated that he has to model 40 odd separate exhaust manifold combinations. I don't envy him at all, but I can't even begin to estimate the lines of code I will require.
I have created a parts/research hierarchy tool. For creating and maintaining giant part trees. For spreadsheet Monkey Daffyflyer to use, as well as the community.
It will be released to the community, once the research/parts system is fully tied down to a point we are confident that it won't change. Which could possibly be a few months, once the game is in a fully playable state and there is nothing we have missed.