The silicone sheet that presses onto the tray of your machine is not the most attractive thing I’ve ever seen, but it is one of the most useful. Marketed under various names, including Supreme Slider, Silicone Slider and Free Motion Glider, these sheets have a tacky side which easily adheres to the bed of your machine. Most of them just have a small hole that is to be positioned right over the needle slot, but I’ve seen one brand that has a big enough opening that the feed dogs are exposed. I personally have enlarged the hole on my slider to expose the feed dogs because I can then leave it on the machine all the time, not bothering to take it off for straight stitching and back on for free motion.
Why I love this: I think that it gives you that additional ease of movement for any kind of sewing, not just free motion. If you like to work with flannel, fleece, Minkee or any of the cuddle type fabrics, they tend to build up static and are a bear to work with. The slider makes it much easier and I don’t know how anyone sews with that type of fabric without one.
This is not an inexpensive tool, but well worth the $ invested!
Pic copied from Sew Steady. (Thanks!!)