I have a number of plastic bottles (old shampoo and conditioner containers) that i have saved for insertion. They feel good to fill with warm water. Various sizes ranging from 6" to 8" in girth.
My favorite has been a shaving gel can... the rounded cap makes for nicer insertion ( I have permanenetly secured the cap so it cannot come off inside!) It is 6.5" in girth and has given me enormous pleasure over the years.
I have also made my own dildo from time to time by rolling up a chamois cloth around a stiff tube and covering with a condom. I can play with size and stiffness depending on how I roll it and what I use as a core.
There have been a number of vegetables that have been repurposed over the years as well! Cuccumbers and butternut squash come in so many size variations that make it fun to experiment!