Isn't it fun how items which would be ordinary and run of the mill to others take on a completely different role if you're tickle obsessed.
The bristles of an upholstery brush, when skilfully applied to bare soles, are... OMG... OMG... hard to put into words just how much these tickle.
I've seen some weird tickle tools. Theraguns do wonders at tickling me and I didn't even know I was ticklish on my feet! I used one against my sole and it got a giggle out of me.