Trick Opening Box




Introduction: Trick Opening Box

We are two brothers...usually he cooks and I build...and together we are fathomlis!

This is a box. A box which is quite tricky to open. It's called (as you've seen already) a trick opening box or a puzzle box.

I first saw this design in Tim Rowett's (Grand Illusions on Youtube) video on trick boxes. It fascinated me. And it looked like the easiest to make of all the boxes he had shown. I am not really a woodworker and do not have much experience with woodworking, but nonetheless I went ahead and made the box. I love puzzles and I love boxes and this project combined them both. So to me it was perfect! A project...for the love of boxes and puzzles.

My finished box is not at all perfect...but it works. I think there are lots of woodworkers and artists that will be able to do a better job, but for me this was great.

This box uses centrifugal force to open it. You have to spin it! Check out the video.

Step 1: Planning...

Planning for this progect is crucial. Without proper planning you could wreck it. Think and understand before starting. Work out what you are going to do and how you are going to do it. Also fully understand the locking mechanism utherwise you might blow it.

Step 2: Understanding the Locking Mechanism Before Starting.

Understanding the locking mechanism. As you can see on the picture the mechanism works with nails. To lock the box, you place the lid on and tilt the box which causes the left or right (depending on how you tilt it) group of nails to fall into their slots. Now when you try to open the box it is stuck. No matter which way you tilt the box one group of nails will always be in their slots preventing you from opening the lid. To open it you just need to place it on a smooth surface and give it a hard spin. Centrifugal force will push both groups of nails out of their slots alowing you to open the box again.

Step 3: Learning From My Previous Attempt.

This was my earlier attempt. It was a fail. I had made the whole thing but at the end I found that it didn't work. What was wrong? I had gone into the project without fully understanding how the locking mechanism works and how it should be placed into the box. I had made both the slots of nails to one side of the box instead of one to the right and one to the left. Now when it was spinned, only one group of nails opened, the other group remained stationary.

Another problem was that my lid was not set deep enough. The result was that I could slide it open.

Step 4: Materials and Equipment...

Things needed:

  • Wood (I used some offcuts from a refurbished piece of furniture)
  • Plywood (I used a piece for my lid but anything would work)
  • Glue (or screws or nails)
  • Saw ( I used a hand saw and a jigsaw but I think precision tools would be better)
  • Sandpaper
  • Nails
  • Pencil and ruler (for marking your dimensions and so forth)
  • Drill

Ok! Lets get started!

Step 5: Base and Nail Slots.

Cut your desired sized base and also two slots of the same length. When choosing your size - take care - you have to have the locking mechanism in mind. The size of your slots will also be decided by the size of your nails and the size of your nails will be decided by the overall size of the box. Carefull planning.

Step 6: Cut Out the Rest of Your Dimensions and Your Lid.

They should be carefully measured and in proportion. Remember: Keep your mechanism in mind.

Step 7: Gluing...

Start by gluing the two small sides. And then glue on one of the longer sides. Only one.

Note: I did not use cold glue but rather a glue gun. More action...

Step 8: Preparing Slots.

You need to be really careful here. Mark the places where you will be drilling by placing the nails on the wooden slots. There has to be enough nails and also enough space between them.

Your drill bit has to be slightly larger than your nails to allow smooth motion, but they should also not be too big as they might jumble around and not slide perfectly into their slots.

When drilling the holes into the slots you have to place the slots precisely over one another so that the holes go straight through the one and straight through the other one as well. The holes have to be precisely alligned.

I used a wench to keep them presicely alligned above one another and then drilled the holes.

Step 9: Making Sure They Fit.

The holes need to be presicely alligned so that a nail can fall into one hole and smoothly into the next hole as well.

Step 10: Gluing the First Slot.

Here again very careful planning is needed and a few things should be kept in mind. You will be gluing your second slot to the underside of the lid and you must make sure there is enough space for it in front of your first slot. Another thing, your first slot must be to the right/left of the center of the box (you can see on the picture that I drew a center line in pencil). Then the slot that will be on the lid must be to the opposite side of the center line.

Step 11: Adjustments...

I glued a piece of plywood to stop the nails from falling out. Before doing this be sure to put in your nails.

Step 12: The Lid's Slot.

Here you should also glue on a strip of plywood or wood to stop the nails. On the lid you can also see my center line so that I glued my slot in the right place and correctly alligned with my other slot. This is important: the holes of the two slots have to be precisely across from each other.

Step 13: Slight Adjustment to the Nail Stopper.

I added a piece of hard cardboard to adjust the length between the slot and the stopper, because my nails came to far out and that resulted in the nails falling out.

Step 14: Glue Last Side.

Before doing this be absolutely sure the locking mechansism works. Then you glue it.

Step 15: Adding a Lid 'knob'.

I used a glass pebble, but you can use basically anything.

Step 16: Varnishing and Optional Lid Art.

For the 'lid art' I just drew a question mark with a pencil. It looked quite nice. If you have a laser, you can of course use that.

Step 17: The End...

Done! Now you can safely store your sweets. Ha ha. But it could really work! You can also challenge your friends to open it and when they do, they can have the sweets.

Thanks for viewing this instructable and please consider voting. If you have any questions feel free to post them in the comments.

Hand Tools Only Contest 2016

Runner Up in the
Hand Tools Only Contest 2016

Make a Box Contest

Runner Up in the
Make a Box Contest

2 People Made This Project!


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21 Discussions

Nice box! I really like how it looks too.

I've seen this puzzle box before on youtube and was allways wondering what would be the best approach to make one myself. thanks foe your contribution. This will be very helpful in building one on my own!

I might make one of these out of Lego

I liked that you gave a good description of how the lock works. Although your box is not the neatest box it does work and is a good training tool to build another. Your box, the video on trick boxes, and your suggestions helped clear up a few questions I was thinking to ask. Overall I think it was a good instructable and I will add it to my collection of future projects. Thanks for your entry and good luck in the contest.

1 reply

Thanks for putting this on instructables. I built a modified version of it and made it a geocaching container.

A problem that I ran into when making this box a little bigger is that I put the locking mechanism on one side of the box instead of across the center, so the nails always locked. Don't make my mistake!

1 reply

Yes, that is also what happened to my first attempt. But we learn with mistakes...

Great little box. One simple suggestion. In step 5 you could cut the nail slot pieces as one piece and not cut into two pieces until after step 8 where the nail holes are drilled. This would be a simple change to make the nail holes register accurately with no fuss.

2 replies

Yes! That's a good idea, thanks

You're right!

Great, I got a wench to hold mine as well! She didn't mind.

I like it. Nice job!

Such a clever design!

got my base and the first two sides glued up, going to make mine 22x17x11 cm and out of 18mm pine, as well thats what i have loads of off cuts of laying around..... hopefully get a bit more done tomorrow when the glue is set

2 replies

as i say just started, as i cut the wood it split so the third clamp is holding the split wood together while drying, i think i will conceal the mechanism aswell, will take a few days before i hit the i made it,

ps, sorry the desk is a mess, working on a couple of other projects aswel but had to give this a go so just knocked chopped a few bits to start the gluing


this is really cool!!