I have no clue how to flatten a 1.8 skin to turn into 1.7, you know flattening the 1.8 body layer on the skin, I first posted it PlanetMinecraft and a chat mod replied, I can't figure out what he did it's all very enigmatic to me, he messaged me the download for a skin I asked to be flattened and asked about his method and he hasn't replied since and now I'm starting to like another skin more, then I posted a thread here and now I'm starting to get impatient, I need some help and asking Reddit yielded unhelpful results which worsened my patience on this whole problem.
This software is now useless because Mojang killed the legacy skin server (skins.minecraft.net) from a statement from Dinnerbone on their bug tracker.
Like someone fork it then make the changes to make it work again but that'll require like an API call to convert the name to uuid, then get the uuid's skin then decode the base64 string and poof you have the player's skin...
I had to make a PHP file to make my Skin API to work again but the code is a mess, there's no "cache" inside but within Minotar (legacy PHP code) does have a 24-hour caching system in place
I hope @Paril will someday update it but the last update was in May 2016... Well time to ditch MCSkin3D and use NameMC then... RIP :'(