A new online constructor of impossible figures was opened as a part of community of the site Impossible World. The constructor allows to design your own impossible figures from cubes in Oscar Reutersvärd style. The figure designer is on the screenshot below.
You can choose, which corners you want to cut from the cube by selecting appropriate cubes at the line of blue cubes at the top of the toolbar. Then you can drag cube by mouse from the drag area to workspace. Cubes on workspace overlaps each other in order of drop.
You can save your figure by clicking on diskette button, and then post your figure to the common blog of the Impossible World community.
Note, that impossible figure constructor is supported by Google App Engine and you should have a Google account to create your figures. But you can see figures by other members of community freely.
Visit the community to create your impossible figure here http://im-possible.appspot.com