Three Construct Puzzles with Key

The key or "object to be constructed", is a partial pyramid made from 30 cubes. The array of cubes that forms the surface adds a degree of difficulty. Puzzle 1 has 3 pieces all ten-cubes;
puzzles 2 and 3 have 4 pieces, 2 eight-cubes and 2 seven-cubes. In puzzle 2 the 8-cubes are identical and in puzzle 3 the 7-cubes are identical. OpenSCAD code is included.