Doesn't work right now.
If I pick a unit to build it tried to take over all of that specific unit and make it deliver, even if it's not a delivery unit. It then freezes shortly thereafter with all of the units just crowding around the factory.

I haven't been able to re-create the conditions that led me to the bug you mentioned. My best guess would be one of two things:
- Another processor is accessing the Mega: In this case, to attempt to "play nicely" with other schematics, the allocation module will bypass controlled units of the selected type. The processor is pretty fast, which would allow it to grab new units.
- In v7, there's a new feature to set the mode of support units (repair, mining, assist player, etc). I found that *sometimes* the selected mode prevents processors from grabbing the support units (like Mega). In this case, I've set them to mine or repair and the units are grabbed by this schematic's processor.

If this isn't it but you can figure out what caused the glitch, I'd be happy to take another look.

Great explanation of the process for "delivery unit selection" below by the way. It was a compromise between complexity and functionality.

for those trying this schematic out but are getting lost - there's a sorter to the bottom right of the logic display. whatever unit you want to use to collect and deposit resources needs two selections of this sorter, one after the other. so if you want to use mega as the unit to collect and deposit resources, then you click on sand first, then metaglass a moment later. then the mega unit will show up large in the logic display, and will be confirmed by the third "message" block (from the bottom right). to go back to the menu to select a different unit, click once on the button that's to the top right of the logic display. to select what units you want the factory to BUILD, you select directly from the factory on the bottom left. if you want to produce air or naval, you need to delete that bottom-left factory and replace with an air or naval factory. this is a very cool schematic, and units get built very quickly. hopefully [hyper.focused] can fix the small bug i mentioned.

i tried this schematic on the latest version of mindustry. i already had a fleet of mega, but when i afterwards selected mega using the switch (sand, then metaglass), it did not select the existing mega at all. however, if i build new mega from scratch while the schematic was set to mega, then yes, it picked them up and used them. bug?

I'll need to work on the documentation.

The idea is to use the switch to indicate you want to change the drone. The units/ore show on the screen to indicate which ore to select using the sorter for your choice. The first choice is for the tech stream, then the model. There's a message block with some details that should help guide through it in game.

Hope that helps. I tested it fairly extensively when I published it, but if it's acting up please let me know.

This is great! I can't seem to select another drone, however, I turn on the switch, multiple units display on the screen, then the switch turns off. How do you select the desired unit?

Some of the logic relies on v7 commands, so you need v7 for this to work.