****o, I just wanted to apologize to you for not getting back more readily to your question. We were having some technical difficulty with our site. In regards to your mylar question, I have to honestly admit that the only mylar I know of is the thin and filmy type (like on balloons), however, if yours is a "thicker" type mylar, then you should be able to use one of our bits from our "Carving/Engraving" selection. We make some "very small" tipped ones, which are from #105 - #113. These are for detail engraving, carving, and routing in wood, fiberglass, plastic and soft metals. We also do have larger ones and the best one for "slotting" would be #199 which is 3/8" across. Now, if you otherwise just prefer to use a "Cut-off Wheel" and literally "drag" it through the wood partially (not going all the way through), that should work for you as well. Do remember though, with a "wheel", it really can only go straight or angles, no curves. To view these bits, please visit our website at www.dremel.com
. Should you have any further questions, you can now find a "Live Chat" on our website or you can call one of our representatives at Dremel on our toll free phone number of 1-800-437-3635, Monday-Friday, 8:00 am - 6:00 pm, CST.
-Beth at Dremel