Take a lens holder/focusing frame from an old photo enlarger (you youngins will need to Wikipedia that...it was something we had to use before digital photos) and screw a Dremel into it
http://beelzebubby.deviantart.com/art/Homemade-Dremel-router-base-66042700
http://beelzebubby.deviantart.com/art/Homemade-Dremel-router-base-66042700