As far as I know you can't run Lightwave on a standard Amiga (someone please correct me if I'm wrong). The Amiga version of Lightwave came as part of the Newtek Video Toaster Video production Zorro Hardware and required the Video Toaster Hardware to work as it utilised the hardware for much faster rendering.

There are many other 3D packages on the Amiga that you could use and they will work on an unexpanded A1200, but if the Amiga had some fast ram and a FPU (floating point unit) as part of an accelerator card it would make a huge speed boost when rendering frames.

I originally started out on the Amiga using Caligari 3D which while good at the time wasn't the easiest to use (later became Truespace on the PC), and over the years I also used Aladdin4D, Cinema4D and Imagine on the Amiga and they worked very well.

You will probably recognise the name of Cinema 4D as it is still one of the leading PC/Mac 3D applications with version 10 just being released, and it started life on the Amiga, just like Lightwave did.

Out of these I would recommend you give Cinema4D or Imagine 3 a try as they are probably the most advanced 3D apps released on the Amiga. But Aladdin4D was also good with a quite nice WB style interface.