Tools & Supplies
1. Toothbrush (Walgreen's translucent plastic variety for this Instructable)
2. Small cutting tool or saw (could be a Dremel tool)
3. Small file
4. Masking tape
5. Small torch or flame
Cut the head off of the toothbrush with your saw or cutting tool.
(The cutting process can generate friction to cause enough heating of the plastic to melt around the blade ... be wary of that. I lubricated my jeweler's saw blade with wax to help prevent this).
File the cut surface of the handle so it is straight and flat. Also, file the cut area of the toothbrush head so it has a rounded surface.
Tape the bristles of the toothbrush head to protect it from the heat of the flame. The bristles will singe very easily otherwise.
Use tape to secure the head of the toothbrush to your work surface (this will keep it from moving when you attach the handle).
WARM the top of the toothbrush head with the flame (it does not need to melt like the handle will).
Heat the end of the handle with the flame (it may even catch fire for a moment... this is a sure sign the handle is ready to apply to the head). Blow-out flame before applying to head.
Steadily (and carefully) apply the toothbrush handle to the head. It may remain soft for a few seconds so you'll have a little time to adjust it. Do not touch the molten areas with your fingers. Once set, let cool. If it needs further adjustment, carefully warm up the connection with the flame and adjust. When reset, let cool.
Remove tape and you're ready to use your brush.