I have recent taught myself to do free motion stipple. Have a look at www.sharonschambernetwork.com - an excellent tutorial. I also learned the value of sticking some teflon sheet onto the machine (with masking tape) with a hole cut in for the needle. On line I fould a Supreme Free Motion Slider which would have cost me about $40 to have sent to UK. However here in the UK we have a store called Lakeland and they sell teflon sheet under the name of "magic carpet" for far less, about £5 I think. Teflon sheets are also called craft sheets and I found these on line also but not very big. The teflon just takes all the effort out and you get nice smooth lines and curves.
Jane