Hmmmm I am not sure about this tickle tool to be honest, I mean if used gently enough with the soft ball points on the hair brush might feel nice and tickle a bit on the soles and heel-however if a ler or switch got real carried away in the heat of the moment-excitement of tickling the lee whether that lee be bound or not bound-it could hurt-I mean soles and heels are some very sensitive areas-very sensitive usually very ultra ticklish skin tissue. I would think if it is not slow and gentle it would hurt and not feel real tickly-not feel real good. I would think soft fluffy feathers and stiff feathers would feel lots better and be more effective and powerful as tickle tools, in a playful ler or switch's personal tickle arsenal.
I know that Crest Spin brush (electric toothbrush) and Oral B Pulsar-(electric toothbrush but one with not rechargeable batteries) tickles like crazy insanely!!! I know soft fluffy feathers tickle also especially when slowly trailed and dragged on the sensitive skin exposed-know stiff feathers tickle like mad too, can drive one bonkers, tickle insane especially when applied to the soles, heels, and btw the toes and underneath the curled toes whether lee is bound or unbound. Know that chopsticks flat end and the tool in general works wonders, especially btw the toes and underneath the toes, gentle sawing it back and forth, especially slow strokes along the sole and heel and espec the ankles slowly up and down along the legs -don't forget the back of the knees, front of knees and back of calves and legs too..........mmmmmmmmm chills powerful.
However I don't think that a hairbrush would tickle that much oh maybe lightly tracing it on the back of the nape and maybe gently tracing the hairbrush w soft ball points on the shoulders and lightly on the tummy and yes even the ribs and sides if gently enough-short amount of time long as slow and gentle and not fast , not rough. Also sure the back of calves and legs might work too and probably the lower back of the spine, lightly applied to the back slow and gentle, but besides these exceptions other than that don't think a hair brush w soft ball points would make a very good tickle tool. I could be wrong but don't really see a hairbrush as tickling too much. But a really neat and a great thread you started and enjoyed reading it.
But yeah I also have heard and read that the Sonic Care is EVIL and Wicked I have heard, don't know only have had the Sonic Care used on my feet, ribs, and sides, and tummy once or so and I could not take it for real long it drove me bonkers-this was during the first time I was playfully restrained with underbed restraints and tickled-casual friendship- private tickle session with a couple who were bear and I's friends, after meeting online-it was intense and quite a overwhelming powerful experience having my feet, ribs, and sides, and tummy tickled with the sonic care, oh man was that intense....made me twist and squirm and laugh hysterically after a half hour or 2 of being tickled-I "broke" not just from only sonic care but also from having my hubby and a other guy tickling me while first time being really bound-made me go crazy.
It was a great fun positive tickle bondage experience, then after that I was hooked to being tickled while being playfully bound and after that night-my love to tickle and being tickling expanded from there. But got to say I have not really ever had my feet really tickled by hair brush not sure how that would be, not sure if I would enjoy that or not. Yet sure many have been tickled by hair brush been driven "tickle bonkers"