Hey! I've noticed that the function registerBlockIcons:

@Override
public void registerBlockIcons (IIconRegister iconRegister)
{
    String[] textureNames = getTextureNames();
    this.icons = new IIcon[textureNames.length];

    for (int i = 0; i < this.icons.length; ++i)
    {
        this.icons[i] = iconRegister.registerIcon("tinker:" + textureNames[i]);
    }
}

in https://github.com/SlimeKnights/Mantle/blob/master/src/mantle/blocks/abstracts/InventoryBlock.java
have hardcoded "tinker" as a prefix of the assets path which only lets a mod with the assets path "tinker" use this function. I've failed to realize if anyone can use mantle for their own mods outside of tinkersconstruct and if that's not the case please close this issue!

good catch

should be taken care of