Why convert all 3 items needed to build rocket parts into new items?

Why not instead have a recipe that created rocket parts from the 3 ingredients and change the rocket silo to assemble a rocket from 50 rocket parts. I think that would make much more sense than just mapping the 3 ingredients.

It creates three new parts because the base game uses three parts and the mod is trying to be as unobtrusive as possible.

My use case that inspired the creation of this mod was that I wanted to ship blue circuits from a rocket silo. With this mod, I simply select the rocket recipe that uses RCU+LDS+fuel, and make a quick change to my production line to create some RCUs on the spot and load them. I don't have to touch the LDS or rocket fuel lines at all. If I had to assemble rocket parts, then I'd have to change how my LDS and rocket fuel were handled, as well.

In addition, if you could build a separate rocket part... what should it weigh? How big should its stack be? What sorts of new base builds could be created by shipping pre-assembled rocket parts around by trains/bots rather than the three components needed? I didn't want to have to answer any of those questions, so I instead created components that are essentially a 1:1 match.

Those questions aren't that difficult, though. The weight of a Rocket Part ought to be the combined weights of its components. Low-density Structures are 5, Processing Units are 3.(3), Rocket Fuel is 10. That gives you 17.(3), which I'd round up to 20, and I'd arbitrarily let them stack up to 20. That gives you a rocket capacity of 50, or two and a half stacks.

As to what kind of base builds - it makes space transportation less cluttered, and more analogous to rail travel. Rockets are your trains, rocket parts are your fuel. Just like you don't ship Coal, Petroleum and Light Oil to your train depots / refuelling stations, so you don't ship raw materials to your silo. This de-facto moves production out of the silo and into the rest of your infrastructure.

I'm not making this post to argue, mind you. I was just thinking of making the exact mod I'm describing above myself, and wanted to see if anyone's built it already :)

I really like your solution. This is very opt-in, and solves the very specific problem of shipping blue chips (or other rocket ingredients). I like the fact that it doesn't change anything else. Just leaving my 2 cents

I see it the same way as polvoazul, this solution is great as a opt-in that is only required at the rockets that are used to ship red chips, lds and rocket fuel.