Thinking Cap




About: I enjoy taking a pile of junk and making something unusual out of it. I like wheeled vehicles, and currently own two motorcycles, two electric bikes that I've built, and an electric scooter pushed by a soc...

I was struggling with ideas for my next project, then it dawned on me.  I needed a Thinking Hat!

Looking around in my shop, I found I already had all the necessary materials to construct such a time-honored headpiece.  The materials used were:

- an old hard hat
- an old power tube from a previous project (
- a toggle switch
- an "AAA" battery holder (and batteries)
- a "mystery" red LED (I call it a "mystery," because it came unmarked in a box of junk parts I bought once upon a time)
- wire
- an empty wire spool
- an old coiled cord
- a little round "thingy" from an lamp
- a couple of feet or so of brass rod
- solder
- heat shrink tubing
- and my old glue

The tools used were pretty simple: a drill, drill bits, and soldering gun

Step 1: Preparing the Hard Hat

The hard hat stood before me like a pure white canvas (photo 1), ready to be magically transformed into a Hat Of Deep Thinking.

My plan was to mount a huge old vacuum tube on the top (sort of like an "idea" light bulb), stuff a red LED up through the base so it would shine through the glass, and wire it all together with batteries and a switch.

Looking around, I realized that the pins of the tube would fit nicely inside of an old plastic wire spool, so I bolted the wire spool to the top of the hat (photo 2).

Step 2: Preparing the Vacuum Tube

The vacuum tube I used was from the power supply of an ancient television (photo 1).  I began by soldering wires to the leads of the LED, then carefully drilling a hole through the bakelite base and stuffing the red LED all the way up to the base of the glass part of the tube (photo 2).  I had marked the wire for the positive side of the LED before stuffing it inside the tube's base so I wouldn't have to experiment when it came time to wire up the circuit.

Since this was a "mystery" LED, I had no idea what it was rated for, so I began testing by applying 3 volts, and then testing a variety of resistors in the circuit.  I wound up staying with 3 volts and using no resistor.  I suspect this is probably a 5v LED, but 3 volts with no resistor seemed to work fine.

Step 3: Installing the Vacuum Tube

I hot glued the vacuum tube to the empty wire spool I had previously bolted to the hard hat, then made a couple of wire bales that attach to the top of the tube (using some unknown lamp part from my junk drawer), and attaching to the hard hat through holes I drilled.  I reinforced all these attachments with hot glue.

I then attached a coiled cord on the left and right sides (through holes I drilled), and hot glued the center to the unknown lamp part I had placed on the top of the tube.

Step 4: The Electrical Stuff....

The electrical stuff was very simple.  I bolted an "AAA" battery holder inside the hard hat, drilled a hole in the front for a small toggle switch, then hooked it up to the LED wires coming from the vacuum tube.

Step 5: The End Result

I have been noticing that simply wearing the Thinking Hat can make a big difference, but when I want to do some really deep thinking, all I have to do is flip the little toggle switch on the front of the helmet and, WHAM, the thinking really gets DEEP quickly!

If you've ever thought, "Gee, I wish I had a Thinking Hat," I hope this little Instructable will inspire you to make one.  Have fun!



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    26 Discussions


    7 weeks ago

    How much would you sell one for


    3 years ago

    You should try the pro version 20.00006 it has a multitude of vacuum tubes and empty spools of plumbers tape.

    1 reply

    Reply 5 years ago on Introduction

    Yes, it is indeed upside down. It's because of the Thinking Cap, you know.....

    daddy spatula

    6 years ago on Step 5

    I really like the hat, but I REALLY like the photo.


    7 years ago on Introduction

    You could adapt a TDCS kit to overclock your brain and make it a real thinking hat! ;)

    This made me lol and kinda reminded me of portal for some reason. Now you're thinking with hardhats.


    7 years ago on Step 3

    The unknown lamp part is called a harp.


    7 years ago on Step 5

    Here is a Demotivation from me to you :)

    I love this instructable, by the way.

    1 reply

    Reply 7 years ago on Step 5

    Ha! Thanks for the comment, and thanks for the link to the demotivation!!


    7 years ago on Introduction

    This is very well thought.
    As a matter of fact as it was conceived BEFORE you built this cap I think that you don't actually need it and you should give it to someone who's thinking abilities want such a boost : be kind to your neighbor ! …

    2 replies

    Reply 7 years ago on Introduction

    Well............... Actually, I didn't think about building it until I taped the vacuum tube to my head and felt its energy filling the great void that exists between my two ears. Then a voice spoke to me saying, "Must get old hard hat, empty wire spool, LED, and lamp part 'thingy' and assemble into a Thinking Hat!" I've often wondered if the voices only speak to me....... Enjoyed your comment!


    Reply 7 years ago on Introduction

    Aaaah ! That explains…
    So make a good use of it. You already did by showing how useful it is.
    Guess I'll end up making my own ; French style of course, I don't want my fellow countrymen see my think with an accent (but then again !!…à.
    Enjoy your week end as much as I enjoyed your instructable ! …

    The nerdling

    7 years ago on Introduction

    3 years later

    2 replies

    Reply 7 years ago on Introduction

    Wonderful, yes, but silly?!?! I mean we're talking about a real, carefully designed and tested Thinking Hat. When it come to thinking, I need all the help I can get! Thanks for your comment!