A change to the way tier 2 and tier 4 parts, microscopes, and construction materials are made
What I am suggesting is a interesting change to the work flow for more advanced so instead of needing 4 separate buildings to make them you only need two. However, these buildings would be upgradeable to allow for more inputs but they will require more power and more workers.
The idea is you can make tier 1 and tier 2 items in the same building and tier 3 and tier 4 items in the same building by adding an extra input and tweaking the recipes for them.
By doing this the work flow becomes less messy and the you conserve space that could be used for other things that might be added to the game in the future.