If you’d like exact rates, you can use belts of various speeds & smart splitters, eg.:

Need 300, so take a higher belt (eg one of the 455) and smart split off into a mk3 belt (270), and overflow the rest. You should now have a full mk3 270 belt and 185 remaining (overflowed). From that you can smart split into a mk1 (60), and split it in two (30, 30). Take one of those and merge it with the 270 from before and you’ve now got 300, with 125+30 remaining for more siphoning off. Basically, 300=270+60/2.

Similarly, you could do 2000=1200+780+60/3. The rest is left as an exercise to the reader.

I’m a little confused on the exact request here. Do you have those pictured lane rates now, and need to combine/ split them into the ratios above (2000, 300, e.t.c)?

projects/[rust|cpp|python|..]/proj-name

Your son has good instincts!

I actually came in here to post just that. It’s something that, while I’ve vaguely known, is not something I typically remember to do - I’m usually returning or collecting Vecs all over. I shall be now diligent & intentional from now on.