One of the major problems of the synthetic race is early game population. You barely have any, which means you can barely colonize anything. Your population doesn't grow naturally- you have to build it which costs mineral resources and time. It takes like 75 social production points and like 1 Durantium and 1 Promtheum to get 0.5 pop.
So the idea is simple: when you make your custom race, combine synthetic with prolific. The key is the prolific's +50% pop upon colonization. The idea is to custom design a colony ship with TWO colony modules, and put 6 pop into that ship. When it colonizes, that 6 pop turns into 9 pop thanks to prolific, meaning that you just got the equivalent of 225 social production points and 3 Durantium and 3 Prometheum worth of gains with only a single colony ship. The key traits other than prolific are:
Movement +2 (bonus) - so your colony ships can still move around without engines.
Dense +2 (bonus)- so you can fit two colony modules on your ships.
With this strategy, you can avoid the biggest problem that synthetic races have: slow starts due to low population and no natural population growth.
If you're a developer, please don't nerf this. It's f-ing awesome and it's a weird exploit most people aren't going to use anyways.