Even though I don't play retro games, I still love the old box and figured that it should be honored in some way. Thus a concrete version would be great since it could live on in my garden as stepping stones. That way it would still provide a path for me to enjoy,
Here's how to make them.
Step 1: Prep the NES - Part 1
After you get the top off, you'll see a few plastic posts that stick out. Cut these off with a Dremel. You now have a top half that will lay flat.
Note: some people are shocked to see a NES console cut up. The machine still works and the top can be reattached if you want. But still, they sold over 60 million of these things and barely any are used these days. Relax.
Step 2: Prep the NES - Step 2
To find more places that need glue, hold the NES up to the light. See a leak? Glue it! Repeat, repeat, repeat.
Step 3: Mold!
I left a 1/2" margin around the NES and used Smooth-On PMC-746, 1.5 qt. set for the mold itself.
Making the mold was pretty standard stuff. Mix the two ingredients thoroughly, slowly pour, tap to release any bubbles, and then leave it for a day.
To get it out, just break apart the box, pop the whole thing off of the bottom, and slowly peel the mold off of the NES.
Step 4: Casting
The cement I'm using here is Duracal and it mixes with a 4:1 cement-water ratio. Cement is tough stuff so you'll want to mix it up with incrementally larger amounts. What I did was add 400g of Duracal to 100g of water and stirred that for a while until it was well mixed. Then I would add another 400g of Duracal and 100g of water and keep on mixing again until it was well mixed. For each stone, I used about 2.2kg of Duracal.
If you look at the 1st and 2nd photos here you'll see my first attempt. Two things went wrong here: the cement wasn't mixed well enough and the mold had undercuts in the vents that broke off when I pulled the mold off. The first time I mixed the concrete I tried it all in one go. It took forever to mix it up and even then it was uneven. It looks distressed, which is kinda cool, but not what I was going for.
I also went over the mold with a razor blade to clean up the undercuts and got much better lines on the vent.
The Duracal was supposed to be able to be removed from the mold after 2 hours. I waited 3-4 hours for these two. It needs 24 hours to dry out most of the way and I was told that it takes 30 days to completely dry out.
Step 5: Set and Enjoy!
Other consoles that would work for this: Dreamcast, the original PlayStation, the original Xbox, 3DO, and GameCube (small stones).
Big thanks to the folks at Douglas and Sturgess in San Francisco for helping me out with all of my mold and casting questions.