You could try this:

Code (Skript):

1. command /newRecipe:
2.     trigger:
3.         set {_i} to iron pickaxe of efficiency 3
4.         register new shape[less] recipe for {_i} using iron pickaxe, glowstone, redstone, air, air, air, air, air

 

I'll try this now. Thanks!

--- Double Post Merged, Apr 18, 2017, Original Post Date: Apr 18, 2017 ---

Errors: ERROR Can't understand this condition/effect: register new shape recipe for {_i} using iron pickaxe, glowstone, redstone, air, air, air, air, air (Recipe.sk, line 4: register new shape recipe for {_i} using iron pickaxe, glowstone, redstone, air, air, air, air, air')

 

Try to put parentheses `()` around {_i} variable

 

Like this ({_i}) or (_i)?

 

({_i})

 

Just tried it, no difference. Same error

 

Hm. Let's try this:
Replace the set {_i} with this

Code (Skript):

1. set {_i} to iron pickaxe of efficiency 3 parsed as item

 

ERROR Can't understand this expression: 'iron pickaxe of efficiency 3 parsed as item' (Recipe.sk, line 3: set {_i} to iron pickaxe of efficiency 3 parsed as item') 18.04 00:04:02 [Server] ERROR Can't understand this condition/effect: register new shaped recipe for {_i} using iron pickaxe, glowstone, redstone, air, air, air, air, air (Recipe.sk, line 4: register new shaped recipe for {_i} using iron pickaxe, glowstone, redstone, air, air, air, air, air')

Error

 

Alright, let me try this out on my test server, I'll get back to you in a minute

--- Double Post Merged, Apr 18, 2017, Original Post Date: Apr 18, 2017 ---

Okay I got it. Whilst doing this, I also realized that I only had 8 items set for the recipe, so that was one of the errors.
Anyways, here is the code:

Code (Skript):

1. command /newRecipe:
2.     trigger:
3.         set {_i} to "iron pickaxe of efficiency 3" parsed as item
4.         register new shapeless recipe for ({_i}) using iron pickaxe, air, air, air, air, air, air, air, air
5.         send "&4[&l!&4] &rNew recipe registered for &aIron Pickaxe of Efficiency III&r."

 

Just for future reference, would I need to change the varible {_i} to something else (Ex: {_t} ) if I wanted multiple items to share this same formula?

 

No, you could just re-set it inside the command.

 

I just tried the shapeless recipe. It works fine. I tried tweaking it to do this

command /newRecipe:
trigger:
set {_i} to "iron pickaxe of efficiency 3" parsed as item
register new shaped recipe for ({_i}) using iron ingot, iron ingot, iron ingot, air, stick, air, air, stick, air
send "&4[&l!&4] &rNew recipe registered for &aIron Pickaxe of Efficiency III&r."

command /oldrecipe:
trigger:
reset all server recipes

and it just gives me a regular iron pickaxe. Anything I can do to make it enchanted?

 

Just tested it for myself & did some research. Turns out, that Minecraft has higher demand over Plugins for crafting. That means you cannot override existing recipes. As well, your `/oldRecipe` command will reset ALL recipes on the server, meaning that if you run that command, it will not allow you to craft anything.

 

The oldrecipe command doesn't reset the recipes for me. The other thing is really disappointing. How else would I enchant a tool with efficiency 3 by crafting the vanilla way? Thanks!

 

Use this instead of /oldRecipe:

Code (Skript):

1. command /resetRecipes:
2.     trigger:
3.         wipe server crafting recipes
4.         send "&4[&l!&4] &cAll recipes cleared"

There is no way for you to replace the vanilla crafting recipe at the moment. Sorry.

 

I've seen it on some servers that use Skript. I believe it's possible. I've crafted an iron pickaxe on these servers and it gave an efficiency 3 pick.

 

I could quite be a plugin, or maybe there is a hidden syntax that allows to remove all recipes for a specific item or to overwrite them. I could not find anything myself, but maybe you can on the skUnity Documentation Page.

 

Try:

Code (Skript):

1. on craft of iron pickaxe: #Try with the prepare item craft event too
2.     enchant event-item with efficiency 3

 

ERROR event-item stack cannot be changed, thus it cannot be (dis)enchanted