How to Carve a Shrink Cup





Introduction: 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

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

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

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

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

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

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

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

Step 8: 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

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.



    • Woodworking Contest

      Woodworking Contest
    • Casting Contest

      Casting Contest
    • Oil Contest

      Oil Contest

    We have a be nice policy.
    Please be positive and constructive.




    "Nice" not mice! Dratted spellchecker!

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

    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.

    2 replies

    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

    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

    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!!

    "spookshave" ha, A ghostly thought!

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

    1 reply

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


    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!

    8 replies

    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.

    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

    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.

    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.

    xD bamboom... thanks haha

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

    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.

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

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

    1 reply

    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