I was thinking of something that would be relatively different for a new SCP, and here's what I came up with:
A plastic kid's beach pail/sand bucket, complete with shovel, that compels the holder to create a large, elaborate sand castle. The holder becomes physically violent if they are detained from completing their task, and will continue work until finished.
If entered, the interior would be that of an ornate mansion, larger on the inside. Looking out any of the windows would show a different landscape each time, with a variety of possibilities. After a period of time, the castle will collapse, with anyone inside being killed.
Let me know if this is something worth moving forward with.