The Incredible Machine 3 is a 1995 game by Sierra.
It consist of a series of puzzles, each of them being a contraption, partially set, requiring from the player to add the missing pieces and connections, so that when the contraption is started it fulfills the set goal of the puzzle. There are lot of different parts available, from teeter-totters, ropes, balloons and lava-lamps, to gears, motors, lasers, candles, cats and mice.
If you are looking for something that you can play for 10 minutes now and then, this game is nice substitute for card games like FreeCell and Solitaire.
To give you a rough feel of what the game is like check out the Sierra ad for The Incredible Machine 2:
The game is abandonware, and you can get it here (30MB, be sure not to use any speed accelerators when downloading). After you unzip it and install it, you might want to change the compatibility option on the shortcut (right click, then click on Properties, go to Compatibility tab, and there switch on “Run this program in compatibility mode for”, and choose Windows 95) if you have problems.
The game also has option for creating your own contraptions.. Here are two I created:
To play those two contraptions, download the “.tim” files by clicking on the above pictures, and then copy them to the folder where game is installed. Then to load them, when in the game, go to File->Load and click on the picture in the upper right corner of the dialog (looks like a bunch of things). Another dialog will open in which you can choose which set of puzzles you want to play (easiest to hardest), but there is an option for playing “Homemade puzzles” (the last one left of the Cancel button). When you click the “Homemade puzzles” button you should see the list of contraptions you downloaded, and choose to play one of them.