I went through several boxes of space heaters that looked like potential kotatsu heaters, opening the box to read the user manual. Even for the tiny ceramic heater, which is just eclipsed by a box of Kleenex in size, is inappropriate for kotatsu usage. Minimum space clearance - the space you should have free round these types of heaters - is three feet front and back. Unless you happen to be using a dining table as a kotatsu, please avoid these types of space heaters. The smallest space they will safely heat is a room.

Alternatively, you could use no heater at all. Since the comforter creates an enclosed space, it will already trap heat generated by your body. This is also a good way to save on electricity.

12/12/07 Update: From discussions with readers, it seems that the best alternative so far is the Cozy Legs Radiant Heat Panel from Indus-Tools.

Dimensions: 22.5″ x 16″ x 1″
Weight: 8 pounds
Why it would be ideal: “Radiant heaters emit infrared radiation that directly warms the objects in front of the heaters (rather than the surrounding air). If you only need heat by a desk or in a small section of a room, a radiant heater is quiet and will use very little power.” (pulled from site description)

Using triangular and elbow corner brackets, you could build a support for it by attaching these brackets into the table legs. Using triangular corner brackets would give it the most support, but having two elbow corner brackets would allow you to slide the panel in and out, according to the season.
Want to read more?
Project Kotatsu Post #1 - Introduction
Project Kotatsu Post #2 - Construction speculations
Project Kotatsu Post #3 - About heating alternatives

I ended up making my own. My maternal grandmother gave me A LOT of charsiu (Chinese BBQ pork shoulder) when I returned to the states, and I wasn’t sure what to do with all of it. While I read about ramen online in a lame attempt to satisfy my hunger, the internet reminded me that sometimes ramen contains chashu, or the Japanese version of charsiu. Generations of displaced, nostalgia-hungry countrymen have made do with what was on hand, so why couldn’t I?

Originally intended to be shoyu ramen, although it ended up a mishmash of things. The broth was made from lightly pan frying some charsiu with Shiangxi vinegar (Chinese black vinegar) in a soup pot, and then deglazing the pot with some chicken broth. Also added two chopped green onions, soy sauce, sesame oil, and a little more rice vinegar. After the noodles were cooked, I turned down the heat and added a spoonful of miso The mushrooms - reconstituted from dried - added a nice flavor to my broth but ultimately weren’t soaked long enough. Overall, a delicious meal.

Did you notice how nice and yellow the yolk on the hard boiled egg is? Cooked it for a little over 15 minutes (from time I put in in a pot of cold water over medium-high heat) and immediately let it cool in a cup of cold water. Avoids that greenish-gray ring around the yolk. I was also using up a huge stock of gai lan (Chinese broccoli) so I actually boiled the egg in that same pot!

Menma, or shinachiku , or marinated bamboo shoots, or just pickled and seasoned bamboo shoots

The bamboo shoots came from a local Asian grocery store. They actually came pre-packaged and pre-seasoned (about one pound), but I thought that it was pretty disgusting. I rinsed the bamboo shoots out in hot water several times to get rid of the coating and squeezed as much water out as I could.

In a wok with a tablespoon of heated canola oil, I sauteed them over medium heat for 5-7 minutes. Then I added a shaking of brown sugar (actually I used turbinado) and two tablespoons sherry (I had no sake) and Chinese vinegar (the black kind). Let it cook for a while over low heat until the liquid evaporated, another 10 minutes, stirring occasionally.

Add a small shake of either red pepper flakes or a drizzle of chili oil and sesame seeds. Serve hot or cold, alone or with something else. Not an authentic recipe, but it tasted pretty good. I like the crunch of bamboo shoots.

I fell in love with their leather school satchel. Modeled just like the classic brown/black type you imagine students in the US would tote around in the early 1900s or by school children in some rustic European village. They also look like the proto-version of the ultra-expensive, serious-looking gakuesi-kaban, a leather briefcase Japanese middle-to-high school students might carry, although this term also means generally, “student’s bag.”

Leather school satchel, Japanese school briefcase, whatever, they are built like a work horse and put through a lot of damage. They can also inflict a lot of damage, too.

At $350 Working Class Inc’s version was a wee bit out of my price range. They’re currently advertised as $275 when I last checked.

You can find authentic satchels through Ebay.co.uk, although everyone seems to want them too. When did a student’s leather school satchel become so fashionable, so trendy, so it?

If you’re into leatherwork, some of the older books will have a pattern or instructions to make your own. Of the dozens of books I’ve read so far, these are two promising patterns that I’ve scanned for you. Myself, I plan to make one, as soon as my projects stop looking like the product of a disgruntled Boy Scout. The project tutorials are in PDF format, and need to be rotated in order to be read.

Working with leather by William R Guy (1967)
Can’t remember too much about this book, save for this project. Actually, it’s for a strapless briefcase but you can easily add your own.
Guy’s pattern

Creative Leathercraft by Grete Peterson (1960)
Attractively nostalgic with lots of retro photos. Projects are all right, although somewhat dated. Leathercraft technique is skimpy. Not sold on the project photos, which look too nice to be done by hobbyists. But you can aspire to make your satchel look like his! Also without a strap.
Peterson’s pattern

Material-wise, 5-7 oz. cow leather with a regular to firm temper would work well. Machine-sewing is dubious.

Statistics
Name: Bai Guang (白光) nee Shi Yong Fun (史永芬)
DOB: 1920 Beijing, China
Base of operation: Shanghai, Hong Kong, Tokyo, Malaysia
DOD: August 27, 1999 in Kuala Lumpur, Malayasia

Famous for her reputation as a vamp on screen and off.
First stage name was Cao Yu (日出)
Stage name means “white light;” allegedly inspired by the white light emitted from movie projectors.
Most of her work was done between the 1940s and 1950s.
Starred in over 30 films/musicals
Married an American pilot in 1953
Opened a nightclub in Tokyo in 1953
Can be found on the Shanghai Lounge Divas compilation
Died of colon cancer
Songs to listen to:
Waiting 4 U
Autumn Evening

Links
Biography
Filmography (selected)
Death announcement
Pathé 100 re-release of album Lian Zhi Huo

Images

Starring in Blood-Stained Begonia (血染海棠红) (1949)

Random image

With Linda Lin Dai (BG, left)

Dimensions
Dimensions for kotatsu I’ve seen online vary little. I prefer a rectangular table over a square table so I can stretch out my legs. On average, a rectangular kotatsu sold online measures:

• Length: 41-42 inches
• Width: 29.5-31 inches
• Height: 14-17 inches

That being said, you should place a priority on what works best for you, especially when it comes to the height of the kotatsu. If you have longer legs, then clearly you want something higher than 14 inches.

Materials: Table top and table frame
As exhibited by the photo below, kotatsu are made of four major components: blanket, heating unit, table top/tabletop, and table frame. Blanket is not an issue. For the last two items, I was originally thinking of going to the thrift store to cannibalize a table. However, most thrift store furniture is rather cumbersome and solidly built. The legs of a coffee table might serve nicely, though.

I could go to Menards or Home Depot for some lumber but that would also require sanding and finishing, which I’m not keen on doing. So what other cost-effective, suitable alternatives do I have? Hello, IKEA.

Table-wise, coffee tables would work the best, what with their already low height. A bummer I no longer live close to one. However, IKEA does offer some product through their website, which allows me to browse at leisure and wait until I have a weekend to drive down to Schaumburg.

IKEA’s Liden coffee table is nearly perfect and reasonable at forty dollars but is a rather narrow twenty-four inches across. Turning to the Make-Your-Own-Table section, I find a Vikon Amon table top for twenty dollars. Best of all, it comes in various dimensions: 47.25″ x 29.5,” 59″x29,” and so on.

It’s made of particleboard though, so I wonder if it’ll be heavy enough to keep the blanket from moving. Looking at various photos through Flickr, the table tops seem pretty weighty. Regardless, a table frame could be created by either creating a complete table with another Vikon Amon and some legs, or creating a table frame with an open grid with sanded lumber would work, as that would be hidden from view by a heavy blanket.

Materials: Heating unit
A proper kotatsu heating unit will cost about two hundred dollars. I don’t want to spend that much money, nor should I have to if I’m clever about it. Most heat bulbs are conical and wide across the top. Positioned sideways and covered with a wire hood or grill, this would take up more space underneath the table than I would like.

Inspired by heating cables for reptile cages, I found some heating cables by EasyHeat sold at Menards in various lengths for under thirty dollars. Originally for preventing metal and plastic pipes from freezing in the winter, I think it would also work underneath a table. Zero-clearance heating units are important here; if I can wrap heating cables round pipes without worrying for fire then heating cables are my best option.

The image below shows heating cables used to warm floorboards. This is much like the traditional Korean underfloor heating system, known as ondol (온돌). I happened to experience ondol when I was in Seoul and liked it very much. Sleeping on the floor was comfortably warm. Returning to my point however, applying the heating cables in such a manner over the entire table underside is possible and possibly even warmer.

How I would attach the cables in a sturdy manner is another question to consider.

A second option for a heating unit would be a heating mat. I found a small space heating mat through a beer brewery supply site for thirty dollars. I did notice other types of heatering mats for pets and feet, but they require pressure to activate. Only 9″x12″ with a long power cord. Ideally, this would go on the floor underneath the kotatsu as opposed to a heating unit on top. Since legs are on the floor this would make more sense. However, a drawback is that it only warms up to sixty degrees Farenheight. Then again, with such a small space to heat I’m sure it’d be enough especially when you add legs and such.

Conclusion (for now)

So my research has come up with a lot of different and interesting finds for building a kotatsu at home. DIY! My knowledge of electricity and wiring are still lacking so I need to read up on that. Setting the house afire or electrocuting friends are not goals of Project Kotatsu

Want to read more?
Project Kotatsu Post #1 - Introduction
Project Kotatsu Post #2 - Construction speculations
Project Kotatsu Post #3 - About heating alternatives