• Slow transport belt: 1 iron plate + 1 copper plate, 7.5 items / s (half the yellow belt)
• Slow (burner) inserter: 1 iron plate + 1 copper plate, about half speed as a regular burner inserter

Both are unlocked at start, don't depend on any other mods and shouldn't break any other mods.
They are not upgradable on purpose. Once you get "normal" versions, you can trash them or recycle with another mod.

To avoid each of them taking one full inventory line each (depending on mods used), i've moved them after chests.

Credits:
- For belts: Graphics and most code is from "slow belt" by jouni8
- For inserter: Graphics and most code if from "Burner-Filter-Inserter" by V453000 (note that my version doesn't filter)