Here's an inexpensive and very simple crimper for battery cable ring terminals
between 6mm diameter and 16mm diameter (8 AWG to 4.0 AWG).
Just trim off the cable insulation so that the copper fits fully into the terminal,
locate the assembled cable and terminal in the tool, below the sprung-loaded anvil
and whack the anvil with a hammer (on a solid surface) until the joint is tight and secure.
Hardened steel jaws and plated anvil.
BATTERY CABLE CRIMPING TOOL #CRPPNC