An over-engineered solution to a niche problem, but I really wanted to ship blue circuits...

This mod creates three new products: rocket control units (made from processing units), rocket frame sections (made from low density structure), and hypergolic mix (made from rocket fuel), and alternate recipes for the rocket silo that use one or all of these components to assemble the rocket. Since the rocket is now assembled with different ingredients, it makes it possible to automatically load processing units, LDS, or rocket fuel as cargo.

The mod also adds the "Rocketizer," an extremely fast 1x1 assembling machine whose only purpose is to convert components to the new specialized rocket parts. If a rocket silo is just shipping science packs or something, you can just set that silo to use the base recipe and this can all safely be ignored there; the idea is for the mod to be able to more-or-less seamlessly fit into your existing infrastructure and only make changes if they're needed.

Although this mod doesn't technically require Space Age, it's basically pointless without it, so I've marked it as a Space Age mod.

If you like mods that help out with rocket logistics, you might also like Circuit Launchable Rockets, or if you'd rather not worry about rocket logistics, try Telogistics.