Java Item

[polar gulch]

if I want the item to have the thickness of a normal minecraft item, what thickness should I choose? 1 cube?

[scarlet cypress]

Yes.
Though if you just wanna turn a texture into a default item like model there is an easier way

!faq texture-to-3d

[restive bough]

(Result for "texture-to-3D")
Depending on where you wanna have the model there are different ways to turn a texture into a (default-item like) model:
1. Letting the game generate it from a texture (vanilla Java)
2. Directly adding a new item (Bedrock Edition)
3. Letting Blockbench generate it (ONLY use this if the other options are not applicable!!!)

** 1. Letting the game generate it from a texture:**
Create a .json file somewhere inside your models folder and put this code inside of it:

{
  "parent": "item/generated",
  "textures": {
    "layer0": "custom/example"
  }
}``` This will tell the game to generate a model based on the texture `YourPack/assets/minecraft/textures/custom/example.png`.
(Use `item/handheld` as parent instead if you want it to be held like a weapon).

It can be used just like any other model, so you can either replace an existing item with it or "add" it with custom_model_data. You can also load it into Blockbench to edit the display settings.

** ![bedrock](https://cdn.discordapp.com/emojis/526419810272149526.webp?size=128 "bedrock") 2. Directly adding a new item in Bedrock Edition:**
Please follow the steps described in here:
Default like items: <https://wiki.bedrock.dev/items/items-intro.html>
Custom 3D model items: <https://wiki.bedrock.dev/items/3d-items.html>

** ![blockbench](https://cdn.discordapp.com/emojis/340506781111549957.webp?size=128 "blockbench") 3. Generating it in Blockbench:**
ONLY use this approach if you plan on editing it more than what the other option allows you to do!!!
You need to make sure to use per-face uv (_not_ box-uv!) and then do `File > Import > Extruded Image` and select your texture. Then, pick the way it should generate the texture. You can chose between pixel by pixel, line by line (horizontal/vertical) or in as little chunks as possible (area). 
I suggest to always use area for performance. If you wanna edit each pixel/line choose one of the other options.