if you want to make your own try casting it out of latex. You can buy it from your local craft shop and you can paint it on layer by layer onto the sticky up bit. Paint this with oil first so the latex doesn't stick. Allow lates to dry, peel off and continue to build up layers. You will then need something to color it. I should think the paints sold for mask making would do it. Or failing that, ladies foundation and a quiick spray of matt varnish.
If you don't feel like sitting like a clod for a few hours, get some modelling clay, put it around the sticky uppy bit

remove so you have a clay mould. Fill this with plaster of paris or stonecraft powder or similar. Let dry by putting in rubber glove and hanging glove up/ overnight.
Remove clay from around plaster
paint with latex as before Voilla, one personalised TT
Cheers
John