DS was really into making paper versions of MC blocks and characters for awhile. I think initially he may have found some images online to cut out and fold to make cubes. There is an app called PaperCraft that allows you to create your own 3D MC characters. He has also tried making his own freehand (with mixed results). This helped him get his "MC fix" while off the computer.
Another thought: the times that DS does say he is bored, it seems to be a code for "I'm lonely." Often a cuddle on the sofa is what he needs; after a few minutes he'll come up with some new idea of what he wants to create, and off he goes.
