Just thought you should know I added support for this mod to my port of the Advanced Belts mod (https://mods.factorio.com/mod/AdvancedBeltsSA)
The API worked great to add the loader and beltbox!
A couple possible suggestions to the make_tier call.
Add a prerequisite entry for the tech to avoid having to do it outside the call. (loader_prerequisite and beltbox_prerequisite)
Add a weight value (or amount_per_rocket) value to add to the item that is generated.
Are you planning on adding all the new items from Space Age to the stackable list?
