Depending on what you need to make, the ordinary brake press, vice, clamps, straight edges etc. can do nicely.
You still need a crafty flair and be somewhat creative but it can be done.
The trouble I see with those pre-manufactured rust repair sections that you refer to, is fit and finish.
I would like to size them up on a body before handing over the hard earned.
I'm not saying they are junk, just wary of their accuracy and quality.
If anybody on this Forum has purchased and used them I would like to hear their opinion.
You can also have a look at the website in my signature and see what patch panels I was able to make to restore my 1965 Fairlady.
It can be very satisfying to produce your own panels and see a car come back from the brink