Try and get hold of a copy of SILKCUT by The Black Lotus.
You should be able to get it
HEREJust enter Silkcut into the search box.
Its quite new and has proper 3D and I think its the best demo I have ever seen on the Amiga. It doesnt need a graphics card and I think its fine on a standard A1200. You can also download the video version if your machine wont run the exe. Works with WinUAE.