The Tetris objects are geometric shapes consisting of 4 squares with sides connected to each other on a square grid. The shapes are called Tetrominos and were made popular by the creator of the Tetris video game Alexey Pajitnov in 1984 - thank you Wikipedia..... it's time to get specific about the puzzle.
There are many ways to physically make this puzzle. You can cut the shapes out of cardboard with a pair of scissors, use a scroll saw/jig saw/fret saw to cut the tetrominos out of wood, use a 3D printer to make them out of plastic or titanium (just kidding - while 3D titanium printing is available, I expect this would be a costly option) or use a laser cutter to make the shapes out of any suitable material including stainless steel. There are many possible solutions to the puzzle which provides hours of enjoyment. Some solutions are shown in the image gallery.
I used a CNC router to cut the terominos out of 1/4" plywood. The original process was to create the shapes in Visio, export the Visio drawing as a DXF, import the DXF into CamBam, generate the tool paths for the CNC Router and use Mach3 to control the cutting of the tetrominos from a sheet of roughly 14"x14x1/4" plywood. I lost the original raw data files and access to Visio, so this Instructable is a recreation and an excuse to familiarize myself with the 123D Design tool. You do not need 3D design tools for this - a simple pencil sketch on a 1" grid will suffice. But 123D is free - free is good and 3D modelling is fun.
Step 1: 2D Trial
I used OpenOffice Draw to create the 2D model. Unfortunately the app does not export a file format that the CAM software I used understands, so I recreated the 2D model in 123D.
The OpenOffice draw file is attached - NOTE: Remove the PDF extension from the file. The file you want is TetrisPlan.ODG. Instructables appears to limit uploads according to file extension.
Step 2: Model in 3D
Using the 2D OpenOffice drawing as a guide, I recreated the tetrominos in 123D Design. You start with a 2D sketch (would have been great to import the OpenOffice drawing but that's not possible)and then extrude the parts to give them depth. The blocks were drawn as 1" squares on a 0.5" grid. To extrude each piece completely, hold down the control key and select all 4 squares of each tetromino and use the Press/Pull function to pull the surface up 0.25". After doing this with each tetromino (and the 3 block orphan) you should end up with a collection of 3D puzzle pieces.
You can also create a separate design file for each type of tetromino - this would be preferable for 3D printing since you can submit each file as many times as you need to get the number of tetrominos you want. If you submitted this file as is, the 3D printing company will quote you a price based on the overall volume which for this model is high because of all the space between tetrominos. I have done the design my way to simplify cutting all the parts out of a single sheet in one go with my CNC Router. This will most likely be convenient for laser cutting as well.
To compensate for the fact that a rotary cutting bit has a finite radius, the corner of each block has a 0.062" fillet operation applied. A fillet operation is just the 3D CAD terminology for applying a radius to a corner - smoothing the corners in lay speak. For laser cutting, this step is not needed but I think the blocks look better with rounded corners.
The 123D Design file is attached to get you up to speed. NOTE: Remove the PDF extension from the file. The file you want is TetrisPuzzle.123X. Instructables appears to limit uploads according to file extension.
Step 3: Data manipulation
To summarize the steps for CNC Routing see the flowchart.
Once the design is imported into 123D Make, a custom sheet format was created to make sure that the stacked slices format only generated a single layer of plans. By defining the material thickness to be 0.25" which matches the height we used in 123D Design, we get a single layer for construction which is what we want. Click the Get Plans button and export the plans to DXF. The DXF file is imported into the CAM software (Computer aided manufacturing).
Step 4: CAM Conversion
The DXF file from the previous step is imported into CamBam. To cut a long story short, a Join operation is used to convert all the DXF line primitives to polylines, a 1" grid is drawn using polylines and each tetromino is moved onto the drawn grid. This grid is going to be engraved by the CNC so it is not just cosmetic alignment. This will make the wooden terominos appear to have been created from individual 1" blocks to mimic the video game look. Come to think of it, that is an easy construction technique - buy a bunch of 1" square wood blocks and glue them together - but then you wouldn't get to play with all the great 3D modelling tools....
The grid obscures the parts in the attached picture but the main takeaway is that we first load a 1/16" bit into the router and then engrave the grid onto the wood, and then change the bit to a 1/8" bit for cutting out the pieces. I've attached the CamBam file as well as the generated g-code. NOTE: Remove the PDF extension from the file. The file you want is CuttingPlan.cb. Instructables appears to limit uploads according to file extension.
Step 5: Making the puzzle
That pretty much describes what you should do. The pictures show what actually happened.
1. That I forgot to do the grid - redo from scratch
2. That 1/8" end mill was too thick for the grid - redo form scratch
3. 3rd time lucky - all the parts came out great and the grid looks good
Using multiple colors of Krylon quick drying spray paint, each type of tetromino was painted a different color using my outdoor paint "booth". The "booth" is sheets of carboard spread around in a shady area of the garden. Quick drying spray paint limits the chances of insects getting embedded in the paint.
I made the frame on the fly. I machined a 0.5" thick border from 0.25" plywood followed by a solid backing board of the same outer dimensions that was glued together. And that's it. Puzzle done. I hope you find the time to build it. It makes a great gift. I would like a smaller one made out of stainless steel or brushed aluminum for a desk ornament, but that's a project for another day.