When you get to the expense section of TurboTax Self-employed you will see where it says "Enter You Miscellaneous Expenses".
In the attached screen shot you'll see that I entered "Job Materials" to the write you can enter an amount. Below that it says "+Add another row". Here you can add as many labels as you want, or you could lump everything in a category like Job Materials.
The IRS doesn't really care what you call it if it's 100% deductible.
Categories that matter are "Assets (Equipment)" and "Meals and Entertainment"
Big stuff you buy (Assets (Equipment)) has to be depreciated over it's useful life so be sure you keep that separate.
Meals and Entertainment you are only allowed to deduct 50% of so that's got to be separate too.
Pretty much anything else you can call whatever makes sense to you.