So, I was trying to figure out how to make it craft an item, with all the blocks I had. When I found something that worked. ( holding left click, while going between an item I couldn't craft, and an item I could.) I accidentlly kept going and it doubled my item everytime. from 18 to 36 and so on. I ended up with a whole inventory of wood after said glitch. And it was ALL craftable into planks.

Steps to Reproduce:
1. click and hold on a recipe you can craft, and have the means to craft multiple times ( I did log into planks. )
2.move the cursor from the recipe ( the one you clicked and held on ) to one you can't craft. that is right next to it.
3. Move cursor back to the one you can craft
4. repeat till you have all the items you can use in there. then repeat once more.
5. profit - you have duplicated an item :3