If you can’t pull a Marty McFly and travel through time, you can at least look the part with a hoverboard prop like the one he used in Back to the Future 2. Instructables user tnelson5 crafted one in about a day and shared his methods in a post. He used easy to obtain supplies and pretty straightforward techniques for the build. The board base and bottom details were constructed from 3/4 inch foam insulation. Tnelson5 says:

To make the angled tail of the board I cut the overall shape of the board first, then cut it into two pieces 6″ in from the back at a slight angle, then flipped one of the pieces over and reattached it using a hot glue gun on a low setting. I used a table saw and bandsaw to cut the main part of the board but a utility knife would work just fine. I then rounded over the edges by sanding it with 120 grit sandpaper.

The bottom details of the board were cut and carved out of the same foam then sanded. I made a pattern by drawing it up full scale based on my research.

Get complete instructions and a free download for the hoverboard decals at Instructables.