Hashtag Puzzle




Introduction: Hashtag Puzzle

About: Fixer, Finder, Fabricator. I teach engineering to high school students, at St Marys Secondary College in Nathalia VIC Australia

This little puzzle is quite the challenge to solve, and fun to build. The instructable is very detailed with lots of photos and notes as it's written for my beginning STEM students, who enjoy being able to work independently and at their own pace.

The DXF file is there if you want to cut it out on the laser cutter, but as acrylic is not very strong, it is likely going to break the first time you get frustrated with it and throw it at the wall. The real challenge it to make it by hand from aluminum.

You will need.

  • DXF file
  • DXF viewer and printer
  • Hand tools
  • A vice
  • 35mm x 3mm aluminum
  • Tape
  • Scotch Bright.

Step 1: The Files

I would suggest you get a DXF viewer and print the puzzle out true scale, as jpg and other formats just come out in any size the printer feels like on the day, and it can be difficult to scale correctly.

Autodesk does a free DXF viewer, but you do have to change a couple of settings for it to work correctly.


Change from inches to mm.

Calibrate the drawing by typing in how long it is

In the printer settings change the paper landscape and "ignore scale to fit"

If you don't have access to a DXF viewer, the sizes are shown for 3mm thick material, you may have to play around with the scale settings on your printer to get it right.

You could also just put it on the laser cutter but that would be cheating.

There are notes in the photos to help you with printing to paper.

The puzzle 2 file is just a prettier version.

Step 2: Making a Start

First, you will need to print out the DXF file at the correct scale and grab some 35mm x 3mm aluminum.

This Instructable is designed to be used by students who are just starting in the workshop, so there are lots of photos for you to look at with notes. It will guide you step by step, so click on the first photo and check out the notes and move on to the next photo.

Step 3: Make Them All the Same Size.

Your finished puzzle will look a lot better if every piece is the same size, tape them together and start filing.

You can glue the templates to the stacks. There are two different templates one with the hole in the centre and one without they are different and you need both

Follow along in the photos if you get stuck.

Step 4: Cutting Filing and Drilling

Make sure you have both templates and start cutting you need to take your time and cut pretty much on the line, on both sides of each slot, you can then file to fit and drill some decorative holes.

The holes in the centre help identify the 2 "key" pieces, you don't have to put them in but it will make the project much more difficult to solve if you don't.

Check out the photos for more help.

Step 5: Finishing Off

There may be some sharp edges and ugly bits that need attention, so sand the parts with scotch bright and feel if there are any sharp bits that need filing.

The scotch bright will remove the ink and glue

Step 6: Hashtag Puzzle Solved (spoiler Alert!)

If you want to work it out for your self look away now!

If you need help, follow along in the photos.

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    Question 12 months ago

    I really like to make this, but when I try to open or convert the DXF files, I just get a blank page. Perhaps I am doing something wrong? I don't have software that can open DXF so I try to convert them though online converter software.


    Answer 12 months ago

    The link on step one will take you to auto desk view make a free account and you can upload the DXF and print from there