Part bought for a job

Hi. New to books but have been using invoice since 2014.
I have done a couple of jobs this year that I have had to buy parts for. one is a fan belt and the other is a part for a gear linkage. Not sure how to enter the parts and then invoice them to the customer. I tried it through bills but do not think this is right. Do I have to create an item, if so I could end up with lots of items. Can i have an item called parts and edit it each time I use it. My main business is gardening and so my main sale is labour, but I do a few minor repairs on vans and customers machinery so from time to time I need parts.
Thanks