the biggest thing is that there is no need to. All the successful economic designs are already being cloned at a pricepoint most cant compete with. Look at the most popular like...
Beretta 92, cloned by taurus
CZ75, cloned by Tangfoglio, IMI, many others, and now in the $300 range for some imports.
Glock, not really cloned, but you can buy a "glock" without a single glock factory part. There are many that copy the design concept and tweak it enough and make it look different. Glocks aren't widely cloned because they're boring, and cheap, and most glock like firearms cost as much or more. I hear PSA is making a true clone anyway.
10/22 have been, still are
Contrary to popular believe, most Soviet guns are not cheap to make. Slave labor, and 100% subsidy is why those designs were made.
D/A revolvers have never been cheap enough to make good enough to sell, though S/W has been heavily cloned legally and not.
PP/PPK's have been liscensed or copied by numerous makers.
Uzi's have been cloned by a few.
Where I'm going with this, to be copied the design needs to be famous enough to draw attention, like the PPK or Uzi, or unavailable.
If neither applies, your best chance is making a better quality clone at higher cost, like the Bergara 700's, or making a lower quality model at lower cost, which is difficult for makers that cant push their own design.
I know there are designs I didn't name, but can anyone name a well established model that's not cloned or still in patent protection?, other than crazy expensive designs like Lugers (although they are), or FAL's?