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.