Here's some more ideas for you. You are free to edit this anyway you like. I believe after this, I will have no more ideas to give you.
I reached my limit. These ideas just like the one you had earlier can be edited or omitted for your mod. I just make ideas.
The first image is a more involved crafting process for the horse armor. Since their armor is infinate, the making process should be more involved. From left to right,
(1) Melting Process
: Melt Iron, Gold, or Diamond (don't ask.. I know that's the most nonesensable process but you are free to edit when ever you get to this. It makes the liquid version of that.
(2) Making Metal Sheet
: With a crafting table, arrange the metal liquid like so on a crafting table to make a sheet of metal.
(3) Creating Iron Chain
: (Didn't think this one through, it could be done on a crafting table) But, using one iron plate in a furnace makes the iron bars. (You could just use the iron bars originally in the game, if you don't want to create a whole new iron chain. Iron chains would be cool to make chained Armor or even chained horse armor. There's another idea there... I thought I ran out)
(3) Crafting Horse Armor
: This is arranged differently. Unlike most recipes that only do the top this recipe is like looking above the Armour. Requires 4 sheets of metal, 2 metal chains (or bars) and the craftable saddle to finally make the horse armour. I think this process of number of bars needs is probably 16 . If you think this recipe is too hard, you may edit it to your liking.
Craftable Leather Horse Armor:
This can have a crafting recipe to make a thinner leather or just use the regular leather in the game. The recipe is similar except it makes a leather armor. 3 dies added would make dyed horse armor. However, the color variation is lesser than a humans.... unless you really want to do all 64 colors.... knock yourself out, but I just put in the basic 9 colors.
They're just stable decoration ideas. Nothing more. You don't have to make or you can make them if you like.
Top Left: Horse or Donkey Gate
Top Right: Horse Shoe decoration
Bottom Left: Hay Troth Decoration
Bottom Right: Water Troth Decoration