I find using old t-shirts (and dresses and soft pants) for crocheting fantastic: the material is free, you can see the results quickly (a bathroom rug was a bit too tedious for me) and the sky is the limit in what you can do.
On the right I have a few examples on what I’ve done. Pot coasters are great, as it is easy to get variation, I have e.g. made bunnies and chicks for the Easter table and frogs to a children’s party. Personalised baskets/ gift bags have also been a favorite of mine, the bottle bag in the picture was the first one I’ve tried to make.
Once again, I haven’t used any patterns but I got the first idea to make a basket out of old t-shirts from a Swedish women’s magazine called Hemmets. I have used a size 12 hook (not suitable for making kettle holders as the holes get too big for those).