Here are 2 sets of Tangram pieces. One comes in a handy carry case with swivel top, the other set without. That one is intended to be held in a dedicated PolyPropylene box but I have included a box for the swivel case set also. Both should be packed with the puzzles & solutions shown in one of the images.
One of the files is in *.dtd format for direct use in UK schools where Techsoft 2D Design is widely used to laser cut.
I have always loved Tangrams and after making my Pentominoes in a Case, thingiverse.com/thing:5008 , I also made a Tangram classroom set for our Maths department and then this pocket version to give away. It's 100 mm x 100 mm (4" x 4") in 3.2 mm (1/8") acrylic.
Swivel top version:
There are 2 layers of 3mm and 1 layer of 2mm acrylic. The surround of the Top layer was bonded to the Base layer with thin acrylic cement, Tensol 7. An M3 lock-nut is inserted from the very bottom and held in place by an M3 countersunk fastener that also allows the clear cover to swivel.
Non- swivel top version:
This is constructed much in the same way but instead of an aluminium registration pin here 4 square(-ish) dowels are used. In the photo they are in the colours representing the 'houses' within the school. I cut strips of acrylic with the same width as the thickness. They turned out tapezoidal in section due to the kerf of the laser. Heat distortion didn't make things easier either. I didn't get around to trying stock cylindrical acrylic.
Avoid using clear acrylics where you intend to bond as it will show.
The below describes how to construct the Tangram set with the Swivel top, lifted from my Pentominoes in a Case (thing:5008). At the end you will find short instructions about the PolyPropylene box.
Please refer to the screenshot of the drawing for colours vs. settings.
Measure the thickness of your stock material. Not all 3.2mm acrylics are 3.2mm and some shrink more than others when lasering. That's important here when matching the hole to the aluminium rod to be used as a registration point for glueing and as a retainer for the clear swivel cover. So measure its diameter first. For the clear cover 2mm acrylic is more elegant than 3.2 mm and flexes better when swivelling over the pin.
Measure the diameter of your pin and do a test piece to make a matching hole that is tight. The design features 2.3mm holes which you could enlarge by drilling. Change the hole diameter in the design where necessary. A tight fit is needed for accurate registration.
Set the height & apply your settings and then cut the 3.2 mm layers.
Adjust the height and cut the 2 mm clear acrylic for the cover, then countersink the larger hole carefully to match the fastener (drill press / hand countersink tool)
Cut the aluminium pins to size allowing them protrude about 1.5 mm, so about 4.9 mm in total, then file one end flat and the other domed. You could also use brass (hack some motherboard for terminals)
Place the surround onto the base and secure it with the aluminium pins. Insert the 3 mm lock-nut and pass the M3 countersunk fastener through the surround and screw into the lock-nut.
- Using a fine brush or cotton butt, apply acrylic cement to the outside edges where the layers meet and let it go in between by capillary action.
-After a minute or so you can unscrew and then fit the clear cover. Do not overtighten your fastener. Mark how much sticks out the bottom, remove and shorten with a hacksaw. File smooth and refit.
(At this stage you should still be able to adjust or replace the aluminium pin provided it isn't glued in. It can be driven out with a nailpunch or a blunt wire nail.)
PolyPropylene box: The hinge properties of PolyPropylene make suitable for a tabbed design. But, test your settings both for hnge depth and edge curl. Another issue is keeping it flat when lasering. After print previewing I placed some mdf weights in strategic places. Some systems offer hold-down by suction. A papercraft cutter would be more sensible here, I suppose.