Introduction: How to Carve a Shrink Cup

Picture of How to Carve a Shrink Cup

The principle of a shrink cup are, the cup are cut from a fresh log and you put in a bottom made from dry wood. When the cup drys it will shrink and make a tight fit around the bottom. If your skilled enough you can make a cup that are watertight.

This is a easy and quickly made project. I'm using simple tools that most of you already have. My cup is made from birch but you can make it from any wood. It just needs to be fresh cut.

Step 1: Tools You Need

Picture of Tools You Need

Most will already have all the tools needed to make a cup. If you want to go very simple you can make it with only a saw, a knife and a hand drill.
But the marking gauge and the power drill makes it easier.
The ax, the froe and spookshave are used to make the bottom.

If you don't have a suitable knife look at my instructable showing how to make the perfect carving knife

Step 2: Getting the Wood

Picture of Getting the Wood

I went into the forest and found a place with a lot of small birch trees. I have asked the owner and have got a permission to cut a small tree. From one tree you will get enough wood to make a lot of cups.

Step 3: The Carving

Picture of The Carving

Drill the holes before you cut it. That way it is easier to hold the wood, and you don't need a holding device.

Step 4: Carving the Bottom Ledge

Picture of Carving the Bottom Ledge

The making of the bottom takes some patients and some skills. If you want to make a tight fit the ledge in the cup and the bottom needs to be very accurate. If you are skilled enough the cup will be watertight.

While you make the bottom store the cup in a plasticbag so it won't dry out while your working on the bottom. You can all so store it in a bucket of water. Just don't let it dry. If you want to wait to finish the cup you can store it in the freezer until you have the time to make the bottom.

Step 5: Preparing the Bottom

Picture of Preparing the Bottom

With the froe I split the dry firewood into thin pieces of wood. Thy need to be 3-5 mm thick.

Remember to always split the wood in the middle. That way you will get two straight pieces.

If you like you can skip this part and use a piece of plywood or a thick piece of veiner.

Step 6: Carving the Bottom

Picture of Carving the Bottom

The carving of the bottom are very simple but it takes patience to make it as accurate as it has to be.

Step 7: Putting the Bottom in the Cup

Picture of Putting the Bottom in the Cup

The is the exciting moment, will the bottom fit...

Step 8: The Finished Cup

Picture of The Finished Cup

Here you can see more of the cups I made the day I took the pictures for this instructable. As you can see the cups can vary in size and shape, with are with out bark etc.

''Making it watertight.''
If the bottom are accurate enough the cup will be tight. After 1-2 weeks you can test the tightens by pressing the cup to you mouth and try to blow through it. If no air gets through you will be able to use the cup for drinking.
Before I use the cup for drinking I immerse it in linseed-oil, leave it in the oil a day or two. Take the cup out of the oil, dry the excess oil of and leave the cup to dry. I like to let it dry 2-3 months, that way I'm sure that the oil are hardened all the way through.
I only use the cups with out bark for drinking. They are better when you need to clean the cup. I only use the cup for cold drink, mostly mead. I don't leave the liquid in the cup for a long time, if you do that the cup will leak at some point.

Step 9: BONUS: How to Make a Shrinking Bracelet

Picture of BONUS: How to Make a Shrinking Bracelet

The same technique can be used to make a funny shrinking bracelet. First you have put it on you will not be able to take it of again.


Wetfoot (author)2016-12-29

"Nice" not mice! Dratted spellchecker!

Wetfoot (author)2016-12-29

Very mice thought process into creating this "ible", & yes it should work like a champ!

Iceman94 (author)2013-03-02

Just out of curiosity, you said the viking axe was hand forged. Did you forge it yourself, or is there a a company that still hand forges those? Cool 'ible by the way.

jfortier1 (author)Iceman942015-10-26

i do! im TRYING to open a traditional blacksmith shop, just starting to get cold in the evenings, at least till i get a roof on my smithy. lol

morfmir (author)Iceman942013-03-02

Hi Iceman

I did not forge it. I don't have the skills to do a good ax. Many smiths still make handforged tools. The ax I use in this 'ible was made at Lejre center.

If you like a new handforged ax I can recommend
Or one from Svante Djerv or Grandfors

smarty1973 (author)2014-06-23

mate!!!! u have given me so many ideas!! hehe, those shrinking bracelets im thinking could be used as kinda banding on coopered drinkin cups, also i love the birch cups, gonna get my ass out this weekend and get myself some.. congrats on the brilliant instructable fella.. keep it up!!

Quick-tune (author)2013-03-08

"spookshave" ha, A ghostly thought!

KittyF (author)2011-05-30

you leave the bark on. doesn't that peel away after it all is dry?

morfmir (author)KittyF2011-05-30

A little of the bark comes of if you wash it. But if your careful the bark stays intact for a long time.


flio191 (author)2009-08-06

does this work with bamboo? or not really since it's a very different type of wood? great cups though, i live in the city an it's hard for me to acquire fresh wood, but next time I'm out in the country, I might just bring my tools with me! Thanks!

KittyF (author)flio1912011-05-30

Actually, if I remember right, you just cut a section of bamboo just below a joint, then just below the next joint. smooth the inside of the resulting cup and it already has a bottom, the joint.

srilyk (author)flio1912009-08-06

You wouldn't even have to "carve" one with bamboo, AFAIK. Bamboo is naturally watertight and the segmentation parts aren't as subject to cracking as wood is (different growth patterns). I'm not sure if bamboo shrinks when it dries, but if so it should work pretty similar to this technique. Now I wish we had some nice birch trees 'round these parts. Bamboo, too for that matter :P

whiteoakart (author)srilyk2009-12-15

For bamboo, cut right below one of the nodes. That will be your bottom.

The trick with bamboo is to cure it thoroughly.  If you let it air dry, it will crack apart.  To cure bamboo, start with a green piece.  Use a propane torch with a wide flat spreader end.  Slowly, work back and forth over the culm.  It will turn from green to golden brown and smell like popcorn.  Do not burn it. If it turns black, you are going too far.

whiteoakart (author)whiteoakart2009-12-15

BTW, do not try to fire cure bamboo while it is whole.  It might explode.  If you want to cure a long limb, or culm, you must first drill holes through the nodes down the center of the bamboo.  Or, it will go, BAMBOOM!  Please don't throw a piece of uncured bamboo into a fire to see what happens. Someone could get very hurt.

flio191 (author)whiteoakart2009-12-15

xD bamboom... thanks haha

red-king (author)flio1912009-10-12

 technically bamboo isn't wood, but grass... but it might work...

laci37 (author)flio1912009-08-06

Well I think at the segmentation parts it's not hollow so if you want a bamboo cup just cut it on the right places.

morfmir (author)flio1912009-08-06

Bamboo don't grow to that size here in Denmark :-) they become max 1 cm thick. /Thomas

tomman (author)2010-07-19

do you think it would work to use this ideal to make a ring

Kalibar07 (author)tomman2011-01-28

actually i have in the past made a wooden ring.. it is possible just make sure you watch the thickness of the ring and definately use a hard wood.. so it does not split on you

SasquatchKid (author)2010-08-15

I made your lask i keep it in my survival kit

Don,t try this at home (author)2010-07-25

i cant find a berch tree were i live would you sell a cup and if you would how much????

paper sack ideas (author)2009-08-07

for those of us without trees to cut, maybe contact a tree service or landscaping company to see if some fresh pieces could be attained.

You can also go around the neighborhood after a big storm. I've retrieved lots of nice wood that way. Magnolia, black cherry, maple, cedar, tulip poplar. (I make flutes)

hitman_kiwi (author)whiteoakart2009-12-10

You should make an Instructable on making flutes out of wood! the one I found was using PVC.....

whiteoakart (author)hitman_kiwi2009-12-11

Yes, I am actually in the process of doing just that.  I have several Instructables in the works for this.  One will show one of the traditional methods of making a Native American flute from a branch without power tools.  Another will show a more modern way of making them.  With this basic knowledge, I will expand to making a wooden side-blown flute, an end blown shakuhachi style flute, and a wooden saxophone.  PVC is a good starting point.  Whenever I make a new wind instrument, I experiment with PVC first so that I understand the dynamics without having to worry about the labor and skill involved with working wood.

hitman_kiwi (author)whiteoakart2009-12-12

 That sounds awesome! Cannot wait to see   :D

ChaseReno (author)2009-08-07

O.K., sophomoric question here. Why don't you just not carve all the way through the body of the cup? I'm sure there's a reason. By the way, this is one of the better Instructables I've seen. Great pictures and great explanations.

morfmir (author)ChaseReno2009-08-08

If you just carve out the cup and leave the bottom intact the bottom will crack. If you cant to make a cup from one piece of wood you have to carve it a different way. Maybe I will make an instructable about how to make that. /Thomas

corey_caffeine (author)morfmir2009-10-22

please do?

ChaseReno (author)morfmir2009-08-08

See? I knew there was a reason. Would love to see an Instructable on how to carve a one piece cup. Cheers!

corey_caffeine (author)2009-10-22


tomman (author)2009-08-10

could you make a ible for the keg

red-king (author)tomman2009-10-12

 yeah. it would be like "here's a link to this instructable" and then: "use a bigger piece of wood."

Ron-Ray (author)2009-09-27

I would give anything to be younger and be able to spend about a year near you and your family. You know so much about wood, knives and living off the land (so to speak). I can only imagine how much more you know! Only in the past few years have I realized how wonderful and fulfilling crafting things from wood and steel are to the soul and body. But alas... we get older and begin to see the things that are REALLY important in life, just to realize that we are now too old to accomplish them! ... How unfair knowledge and life can be....... (Maybe next time? ;-) Thank you Thomas, for these wonderful insights to life's intriguing basic joys.

tomman (author)2009-09-07

could you use sandpaper for shapeing

morfmir (author)tomman2009-09-07

No, you can't use sandpaper on greenwood. /Thomas

tomman (author)morfmir2009-09-08

thanks any way

peater (author)2009-09-08

That is a beautiful bearded axe!

morfmir (author)peater2009-09-08

Yes indeed it is the best ax I have ever used. /Thomas

gluvsu (author)2009-08-16

What patience you have! These are adorable! Also, a wonderful project for someone on survivor!! Hey why dont you apply for survivor. You would be famous for your cups. :)

morfmir (author)gluvsu2009-08-16

Thanks for your support. What do you mean by applying for survivor? /Thomas

gluvsu (author)morfmir2009-08-25

Its a TV show in US. Look it up on the internet and you can read all about it. People are crazy about watching this show here. The winner takes home one million dollars. I would love to do it but I would never leave my babies for 40 days straight. Maybe when they are teenagers I would lol Tammy

gluvsu (author)morfmir2009-08-18

If you can think up something like that I bet you would be a candidate for the show survivor! Havent you ever watched that? Where are you from? Tammy

morfmir (author)gluvsu2009-08-18

I'm from Denmark and no I don't know the show survivor. /Thomas

whiteoakart (author)2009-08-22

Here is a photo of my black cherry cup. It still needs to dry and get it's coat of oil. I use Land Ark Oil, which is a non-toxic, food safe hardening oil with a citrus oil base.

morfmir (author)whiteoakart2009-08-23

It looks good. And it looks like you have a good fit at the bottom. Very good work. But consider removing the bark. When the bark are damaged like yours it will split even more when drying. /Thomas

whiteoakart (author)2009-08-21

I just finished the carving and assembly of my cup. It was actually not too difficult, although I 'cheated' a little bit. The bottom is made from 3/16" birch plywood from the hobby shop. I was delighted and amazed at how simple it was to hollow the cup out. I used a very sharp Leatherman 3" blade. It was shorter than the depth of the cup, so I switched back and forth, trimming from the bottom, then from the top. As I wrote earlier, the hollowing out process took 32 minutes. Your marking process worked very well. I used a very sharp pencil to get the line for the bottom as accurate as possible. I rough cut it to approximate dimension, then thinned it down to about 3mm thick at the edges. Then I completed the carving to sneak up on that pencil line. Thinning it down before the final cut made it much easier to hand carve that final line. At this point, if I hold the cup up to the light, I can see one tiny sliver of light peeking through the bottom edge. I am hoping that as it dries, it will close up. Otherwise, it looks like it could be waterproof already. Worse comes to worse, I'll seal that little spot with some silicone, but I don't think I'll need to. I made a marking gauge by sandwiching an x-acto blade between two small blocks of wood with superglue. It is not adjustable, but it is what I had at hand. It worked perfectly. The wood is black cherry. I had to cut down a tree at about the same time I first read this Instructable. Perfect timing. I am leaving the bark on, because it is quite nice, like a dark reddish-black version of the white birch you used. The inside of the cup has some nice color variations. Unfortunately, I do not have my camera with me. I will get a photo tonight and post it here. I will let y'all know if it holds water once it dries. Give me a month or so. Finally, If anyone would like a piece of black cherry big enough to make a cup from, email me offline and I will arrange to send some to you. It is very green and moist still. I don't imagine it will cost more than a couple of bucks to send in the US. This may seem a little strange, but I do this all the time with my flute making friends. We send interesting wood through the mail to each other frequently. Morfmir, I will send you a piece for free if you want as a thank you for posting this great Instructable. David A

morfmir (author)whiteoakart2009-08-21

Thanks a lot but I think the cost of sending it to Denmark will be to expensive.

whiteoakart (author)morfmir2009-08-22

I have sent wood samples to Iceland and England and it was surprisingly reasonable. If you change your mind, I'd be happy to send you some. David

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