The Giant Pyramid Puzzle was a gift that I got from some family friends in the late 1980s. It took me several years of off and on fiddling before I discovered a solution to the puzzle. I have since forgotten some of the techniques that I used to eliminate unlikely piece configurations when trying to arrive at the answer, but I did record the layout on a sheet of paper.
I kept that piece of paper with me for years before deciding to save the information digitally, and it's taken me a while to get around to generating a 3D model of the solution. I have used X3D as it is a good open source XML method to represent three dimensional objects.
I have made the model in the solution red as my original puzzle was red. I wrote a script to dynamically create the model, but I've used a static file for display.
Browsers can't display X3D on their own, so the model below is drawn by a small script that reads the X3D file directly. No plug in is needed. Drag to rotate the pyramid, scroll to zoom, double-click to reset, and hover over a puzzle piece to highlight it.