@Schonstudio shared here about her steel bar and brake hose tool to help with finishing. It is a great tool and I’ve been meaning to make my own, but haven’t gotten around to it. The fillets between the bb, seat tube, and stays is always a tricky part to file and I was looking for something similar. I wish I had gotten around to it. What I did find was a toothbrush. the neck is firm-ish and flexible. Worked way better than my finger!
I didn’t grab a picture of it, but I used the round plates below (one is from a press. the other is from an old bearing, I think. both came from a collection of scrap metal working stuff). The 3/8” 4130 tubing bent very nicely. The diameter of the press plate is about 10”.
