If you're scrolled to 120, Cloth Ninja Hoods can get you to 115.0.
After that, any of larger studded armor parts should work (Gorgets only give gains us to 113.8, and you'll probably be making the cloth hoods instead. The studded mempo only gives gains to 115.0. The gloves & Bustier give gains up to 117.9).
Any studded leather items more difficult than the Gloves & Bustier can get you to 120, but if you're not filling BODs (just crafting and recycling) the Studded Hiro sode are the most efficient, using only 8 leather (but gains will get REALLY slow as you approach 120, as 120 is its theoretical gain endpoint, even if the skill could go higher). You'd probably be better off doing studded leggings and/or tunics (with theoretical gain gap being in the high 120s range) after about 118-119, as the gains will be quiicker, even if the leather use is higher.
This Chart gives the leather amount used, and the theoretical skill one can gain to, for each item, based on to what skill one is scrolled to, and is in the order of easiest to hardest (and therefore lowest skill to highest, that one can gain on). Note the term "Theoretical" means that "imaginary numbers" (ones that can't actually be reached, due to skill caps) are given, for purposes of comparison.