So this is a callback to TA, but I'd like to see the nano(?) beams turn off as your economy stalls. This acts as a visual indicator as to how big an impact the stall is having (the longer the beam is off the harder the stall), as well as making the idea of stalls much easier to understand for new players because right now it looks like building continues. Also it adds a further dimension to scouting as you can see how your opponent is faring and whether your raids on his economy are having an impact or not.
This is how it used to work, but a while back I think they changed it so that stall's don't stop building completely, it just effects the build rate.
Better yet, reduce the particle count in proportion to the amount being built. I.e, if the engineer's stalled build rate is only 50% of the full build rate, then only 50% the amount of particles would be produced while stalled.
Just impact how often the nano beam is leaving the production unit in accordance with the modification to build rate. 100% build rate? Nanos flow 100% of the time. 50% build rate? Nano beams have an on-again off-again appearance. 10% build rate? You see only the odd spurt of nano beam. I don't think amount of nanos or nanites is going to work due to zoom level, it needs to be more obvious than that. 20 builders with slightly narrower beams is not going to be as obvious as 20 builders firing their beams in spurts.