Last year, I cut out letters and diecasts from the Ellison machine, and the students made posters showing the letter/diecast in its "normal" state, then slid, flipped, and turned. We labeled each and made them into a bulletin board. This seemed to help!
I do something similar to Nicole by cutting out letters, shapes, and numbers. I then take chalk and make a dotted line down the center of their desks. Students can then manipulate the slide, flip, or turn with the shapes. They feel what each one means when their hands make the movement.
I had the kids trace one of their hands and cut out two copies of it(an extra piece of paper behind the tracing). Then have them put the hands on top of each other and instruct them to flip one hand over and lay it beside the other. This shows them that an identical shape is mirrored when it is flipped. They can also do turns and slides by laying on the floor and being instructed to turn a quarter turn, etc.