This is the Brain in a Jar build I made for the Mad Lab contest and also entered in a contest on Istructables, which is one of my favorite sites. I hope you find it interesting and useful, even if you don't actually need a brain in a jar fro your own haunt.
Every mad scientist needs gruesome specimens and demented experiments on display. Whether actually experimenting with reanimation or just keeping a extra brain on hand for a rainy day, the brain is a classic specimen!
This one is on life support, with blinking LEDs indicating brain activity. What is he plotting in there, and just what does he really think he can do from inside the jar? Mine is called Donovan.
The first thing one needs to know is what the end product should look like. I decided I wanted a brain on wires, with blinking lights indicating activity. The brain should be floating in liquid, ideally bubbling liquid, in a jar that looked vaguely Frankensteinian/steampunk.
I ended up using:
A big plastic pretzel jar from CostCo
Plastic wall anchors
A hubcap from a Chevy
Two 99Cent Only Store "light swords"
Wires from an old TV
A fish aquarium aerator with tubing and a pump
Masking tape, Krylon spray paints, various acrylic paints, sandpaper.
Screwdriver, soldering iron, dremel
I decided to begin with the bottle itself. A brain without a home is a sad sight indeed.
I followed a similar method to my Mad Scientist's Display Cases .
After my football watching, snack food scarfing friends emptied an industrial sized jar of pretzels from CostCo, I had my jar!
I began by cleaning it off and masking everything I wanted to leave clear. There were "bands" already molded into the plastic, so I decided those should become metallic. As with other jars I have made, I covered the bottom so I could light it from underneath later.
After masking, I lightly sanded the uncovered plastic with fine grit sandpaper. Since I use Krylon Fusion as a primer, this is not really necessary, but I think it helps the paint stick better.
I applied a coat of black satin Krylon Fusion as a base. Once dry, I Painted over the black with a thin coat of silver metallic, and then "dusted" with a very thin coat of a gold/coppery color I had. This gave it a thematic / chromatic similarity to my other jars, but still maintained a unique silvery color.
The real difference between a creepy specimen jar and a recycled pretzel jar is the detail work.
I wanted something that really said industrial, hacked, repurposed, and slightly mad. My first details were the conductors / insulators around the top ring of the jar. I know - conductors and insulators are opposites, so which are they, right? It depends on when you ask. They are whichever I think sounds cooler in that particular moment. ;-)
I thought the wall anchors used to hand heavy objects in drywall had potential there. I got two sizes - green and gray - and decided I'd alternate them for visual interest.
This time I had to put them on little sticks to paint. I used an off-white Krylon Fusion as a primer to suggest ceramic. I was thinking insulator at that moment.
So, once dry, I just hot glued them into place around the edge of the jar. Realistically, it may be better to hot glue them in place first, and then paint the jar, but I have not had significant issues with doing it in this order, and it is much easier.
Now that I used the hot glue for the insulators, I can cast other details. I used simple sand casting, as I intended only to put round bolts/rivets/whatever around the perimeter of the jar. Sandcasting with hot glue can make a nice cast iron look, especially if what you want is a somewhat rough, pitted look.
I filled a little container with the finest sand I could find in my backyard. I added a little water, and it was ready to take an impression.
I used a CO2 cartridge from a BB gun to make the impression. I simply pressed it into the sand as deep as I wanted the final cast to be.
I did have to "touch up" the impressions as I went, since the sand would deform some of the earlier impressions as new ones were made.
Once I made the impressions, it was simple enough to fill them with hot glue and wait for them to cool. When they looked cool enough, I used the sticks from the previous step to poke the tacky glue and lift the casts out. Dipping them in cold water would harden them more if necessary.