According to PipeDown :
There are many crimping tools designed for wiring (not necessarily house
wiring but any) that will work with #12 wire no problem. I have also seen
copper sleeves (Ferrules?) for use in crimping wire in the electrical
section at HD and other hardware stores.

There are indeed _many_ crimping tools and sleeves. But few of them
are UL/CSA/NEC/CEC approved for work on AC power wiring. And secondly,
_none_ of them (except the COPALUM device _with_ the hydraulic crimper)
are approved for connecting aluminum wire to copper.

So, telling people to just wander into the automotive section, and use
whatever they find there on their AC power wiring (whether Aluminum or
not) is a very bad idea.
--
Chris Lewis, Una confibula non set est
It's not just anyone who gets a Starship Cruiser class named after them.