In your book, Made by Hand, you list several projects that you wanted to attempt. One of them is to build a still, so I thought I'd share my experiences in home-distilling.
Distilling is fun -- but it's really best as an addition to home-brewing or home wine making. Distilling is a great way to recycle a bad batch of wine or beer by converting it into brandy/vodka. You mentioned the importance of failure as part of the DIY process in your book. Distilling turns failed wine/beer experiments into booze, and I call that a success.
Home distilling has two camps -- purists who aim for the cleanest, clearest neutral spirit, and adventurers who take advantage of the ability to play around making concoctions that won't ever be found on liquor store shelves. Personally, I fall into the latter, in part because I don't have the technical know-how to really fine-tune my still. I make a "bierschnapps" at Christmas-time. Beer is essentially made from the same stuff as whiskey, but with the added bittering of hops. When distilled, beer becomes a great aperitif, with a peppery citrus finish.
This is my inline reflux still. After digging through several hobbyist forums on Yahoo, I found several great plans in the forums at homedistiller.org. They range from tea-kettles with refrigerator tubing soldered to them for pot stills to retrofitted pony-kegs with digital temperature controls. I based my still on one of many excellent design sketches posted by a fellow named Bokabob - it's a variant on his popular "mini-still" design called a "two-cups" still.
Even though I didn't invent the design I made a point of drawing out my plans several times from scratch. I find that drawing out plans myself is a good way to make sure I understand how the thing works.
The boiler is a 20L stainless steel milk pail. Got it on eBay. I had a metal shop cut a hole into the lid and asked them to weld a threaded coupling to the opening. I told them I was building a robot.
This was my first stumbling block. The shop I went to told me they couldn't weld stainless directly to copper - but they could braze brass to stainless. Brass isn't ideal because there is often traces of lead in the alloy. I did some research and learned how to chemically strip lead from the fixture. Once the lid and coupler were brazed, I made a mixture of 1 part 3% hydrogen peroxide and 2 parts white vinegar. Soaking the lid in that solution for about 5 minutes cleaned the brass of any lead in the fitting's surface. I used a chemical lead-test to check and it came up clean. For safety, I repeat the treatment every few months since high-proof alcohol is a solvent.
The rest of the still is copper.
The column is made of 3" copper pipe and stands 4' tall. It has three segments: The "main column", the "head" and the "condenser".
The main column is a 2' segment of copper pipe that is packed with copper pot scrubbers. Steam rises from the pot, up the column, through the mesh. The surface area of the mesh provides the steam plenty of surface area to collect and condense and fall back down the column, essentially creating an environment where the alcohol is continuously distilling, or refluxing, and getting more and more pure the higher it rises up the column. If I take out the scrubbers, I can operate the still like an old-fashioned pot-still.
From the main column, it passes through the head. This was the first thing I ever soldered and it shows. Check out that giant glob of silver solder on it. It shames me every time I look at it. Steam passes through the T-joint in the head and up into the condenser. I built in a port for a thermometer that is positioned right at the top of the main column, so that I can gauge the temperature of the steam, (which in turn allows me to know what is being collected, as different alcohols come off at different temperatures, and you always want to ditch any potential methanol - which is easy because it comes out first.)
Once the steam passes through the head - it moves into the condenser. I coiled about 20' of 1/8" copper tube around a broomstick, annealing with a torch the entire way to keep the tube from collapsing or kinking due to work-hardening. The center of the coil is also packed with copper mesh. It fits pretty nicely into the second segment of copper pipe. The column is left open at the top to avoid a pressure-build-up (pressurized alcohol vapor = bomb).
A pond-pump in a bucket of ice water circulates cold water through the coil. It's important to monitor the circulating water temperature and add ice as-needed to make sure that the alcohol vapor isn't lost out the top. Some people attach their condenser coils to the faucet...but I prefer to use a closed system so that I can reclaim the water and put it to use in the garden.
Back in the head, the collected liquid has two paths it can take - I can open the collection valve, and it will drain off to be collected in a mason jar, or I can close the valve and the liquid level will rise until it reaches the overflow level in the T-joint and get returned to the column to be further distilled. By adjusting the collection rate at the valve, I'm able to increase or decrease the potency of the collected spirit.
A still needs a heat source. I use a gas turkey fryer to bring the liquid almost to temperature, and then I turn off the flame and turn on an electric industrial bucket-warmer belt - it's got a thermostat that allows me to adjust the heat throughout the process. I could use the bucket-warmer to bring the whole thing to temperature, but it would take forever. That said, flames + alcohol vapor = fire-extinguisher on hand at all times. That's another reason to have a built-in thermometer that's reading the vapor temperature.
If I just let 'er rip with the valve wide open, this still can pull beer from 6%ABV to 45%ABV in one go.
Last weekend, I played with the reflux rate and pulled 7 bottles of two-buck-chuck (the cheapest wine Trader Joe's sells at $1.99/bottle) into just over 1.5 quarts of 80% ABV neutral spirit. I split that up into small batches and am soaking a few different fruits and herbs for a week - at which point I'll dilute down to 40% ABV. I'm pretty stoked about the ginger and the orange zest. I'll end up with almost 2L of various flavored spirits.
If I had better conditions, I could probably pull upwards of 90% ABV for a really clean vodka (obviously you don't ever DRINK it at that ABV, you always dilute to 50% or lower). But since I'm doing this in the backyard in the dead of night, always watching for Johnny Taxman...I'll have to settle for what I can get.
Mark Frauenfelder is the founder of Boing Boing and the editor-in-chief of MAKE and Cool Tools. Twitter: @frauenfelder. His new book is Maker Dad: Lunch Box Guitars, Antigravity Jars, and 22 Other Incredibly Cool Father-Daughter DIY Projects