With a base of 21x21 and 6,391 dominoes, this is one of the largest 3D domino pyramids ever created! I was only beaten by two other people, making this the 3rd largest ever. Check out the links below to see the only bigger pyramids.
This pyramid took a little less than 15 hours spread out over 2 weeks. Also, there were 2 scary moments. When building near the top of the 20x20, I dropped a purple domino in. The domino didn't do much damage. I reached my hand in, and pulled the domino out. The second and last domino I dropped in was extremely scary! I dropped a white domino in when building the last layer, and the domino fell down about 6 layers. I thought about just leaving it in there and not doing anything, but something caught my eye. The falling domino hit another domino out of place! I had to get a stick and stick it inside of the pyramid and closely nudge the out-of-place domino back into place.
Someday, I might go for a 23x23. Wish me luck for when I do.