Steve's Carts 2Edit
Upgrades can be used to add or modify features of the cart assembler. An Upgrade can be placed anywhere in the world but won't do anything unless it's adjacent to exactly one cart assembler(one upgrade can't upgrade 2 assemblers). You will know that it's working when you see that it attach itself to the assembler. An upgrade have one or more effects, these effects are what is actually adding of modifying features of the assembler. Effects can be bad to balance good effects on the same upgrade. If you want to know exactly what an upgrade does your best bet is to read how its effects work.
All craftable upgrades are crafted from the blank upgrade.