Calibration cube & kids counting interlocking block

SummaryThis calibration cube is also an educational toy for kids. It works as an interlock construction block, and also as an aid to learn math. The cube is designed specifically to stress:Measure accuracyBridgingStringingOverhangs (in the letters)Layer adhesion (between the large and small cube on top)Details / temperature check (small cone in one side)It's 18 millimeters in the X and Y directions and 24 millimeters in height (Z); the small top cube is 5.85 mm in X&Y, and 6 millimeters in Z (18+6 = 24 mm of total height of the object). Instead of throwing it away, like other calibration cubes, you can use it to build stuff yourself or to give them to kids (WARNING: they must be at least 3 years old, it's a small part).This object takes just a bit less than 4 grams of filament (1.32 meters more or less, at 15% infill), so it is ideal to use this last small piece of filament that is left on your spool. It was designed for the “Last meters” contest of Printables.com.The available gcodes