Slip bobbers eh?
There's a few in my collection....a few dozen......or more.....OK!... I'm addicted to bobbers too! I make them, buy them, collect them from trees along banks, find them floating in the water.....
I use a nail knot tied on the shaft of a plastic Q-Tip for making my bobber stop.
Here's how
thread the line through the Q-Tip
slip the knot to the end of the Q-Tip
Slide the knot off the Q-Tip
Pull the tag ends tight
Clip the tag ends close
Voila...use a plastic bead of appropriate size to protect the knot and stop the bobber's travel. I like a barrel swivel and leader below the bobber to stop the bobber above the bait for casting. This also keeps the line from getting twisted on retrieve.
Try them...you'll like them.
RG