EDGE TRIMMER
I've seen those that use a nail, a pencil and the most popular, the needle tool and they all work well.

I prefer to use an X-acto knife because it gives a smoother, cleaner, thinner, sharper edge.

One uses this by rotating the wheel by hand (either a potter's or a banding wheel) while holding the base of the cutter.

Once the cut is finished I use a damp shammy to round over the top edge

 I keep the edge sharp using a hand held stone and I've found through experience that a blade with a rounded edge is more fun.

Height adjustable to 6" (15cm)

X-acto knife not included

 $29US
 $5 Flat Fee Shipping On Total Order Anywhere In The USA