Board Thread:General Mod Discussion/@comment-27978481-20170830094533/@comment-27190591-20170830132117

Copy and pasting won't help you (and it's not allowed to "steal" code from other mods unless the creator of them permits it). You've to understand what you're doing. Basically you've to create and register a custom ItemRenderer (IItemRenderer) that renders the item with another (in your case 32x32) texture (and maybe applies some transformations) if the player or another entity holds it in his/it's hand. Here is an item rendering tutorial (for 1.7.10 I guess): http://greyminecraftcoder.blogspot.fr/2013/09/custom-item-rendering-using.html.

After reading this you should know how to achieve what you want to do, if not, you can take a look (but not copy and paste unless Mevans would allow it) at the code of the LargeItemRenderer of the LOTR Mod (which you will understand if you've read the tutorial). I guess the mod is for 1.7.10 - in 1.12.1 (the current version) the IItemRenderer doesn't exist any more, because the rendering system of Minecraft changed a lot with 1.8. But even with these versions you can achieve what you want.