Why isn't my item model showing up? All I get is that purple/black cube!

Hi!

I was making a datapack, exept it was getting really complicated and I decided that it would be easier to learn how to mod and make it with a mod instead. After all, I've always wanted to learn how to mod and it will be really helpful for future projects. Anyways, I created a new tool and imported the model I made with Blockbench. I already tested this model in a resource pack, and the model worked great. However, the model uses two different .png textures. I could just combine it into one big texture, but that would take an incredibly long time, and I plan on doing this exact thing with many different models. The .png textures i am using are actually just the diamond sword and axe textures, and i didn't even need to include them in the test resource pack as they are already part of the game. Anyways, when I edit my tool in the mod element thing, I can only select one texture. I think this may be the problem, but I am not sure. Does anyone know how to fix this? Also sorry if this was confusing, if ur confused, lemme know and I can try to explain it better.

Thanks!