My apologies if I am restating a previous thread or if it's already common knowledge. I was just taking a good look at your proposed Domino project and had a question:

http://www.zeta.org.au/~sausage/twistymegasite/domino-project.html

In the second to last photo you say that to hold the two major faces together you are using a washer/screw/spring combo to secure the edge pieces in, thus holding the corner pieces in place as well.

Problem is, how would you go about rotating the two major faces relative to each other? If the washer is fixed, then it would need to "cut" through every piece of one side or the other in order to accomplish. As evidenced by the earlier pic of the disassembled Domino, the major faces do rotate relative to each other. Is there something I am not seeing? I was hope to attempt such a creation but alas it appears that a more custom fabrication will be necessary to make my own Domino.

Here is the link to a discussion on the domino project....

http://network54.com/Hide/Forum/message?forumid=43402&messageid=993515711

It looks like a questionable conversion still. I think the two halves could align well if just one half has the groove cut into them. As long as one groove side rotates and aligns it should be fine but just the whole idea of cutting grooves into the puzzle still seems pretty flimsy. I'd have to say that the mechanism as shown in Cubologists museum is the simplest most effective way to go.

Both sides need a groove cut in - Since the pieces can swap layer, all the pieces need a groove, except for the one edge piece that is attached to the washer to keep the centre aligned.

I didn't stop to consider that. But then, unless you have built-in stops somehow I guess I still don't see how you can expect the center hub arms with washers to stop at exactly the edge cube positions so as to make the face swapping turns possible.

The project was to make a domino from a 3x3x3 and it can be done, I belive but have not tested, with some modifications to the project. The spindle would have to be halved to make it like the actual domino spindle. Have one screw go thru the spindle holding the centers on and holding the halves together. The problem is the edge centers but I am sure that a way can be found to make them behave properly. I think that having a small nail or screw epoxied on to the top and bottom halves of the spindle with half a washer or other round object might work, but this would probably be very lose and not exactly a pleasure to turn. to make it better perhaps a track could be cut into the inner side of the edges, to correspond with an extension from the washer. This would make it turn better and hold it in the correct position, but it would be a lot of work.
To sum up I think it is possible to make a 3x3x3 into a domino by making the spindle act like the one from the original domino rather than try to make the domino work with the spindle. But even if I am right this seems to be to much work for such a simple end result.
I hope this helps and that my idea of changing the projects spindle rather than pieces can lead to someone coming up with a better simpler plan.

Jin is right. The process does have problems. If I changed the design to create the axis piece like in the original domino, it would work ok. (Sorry it's taken a while for me to write this)

I was contacted the other day my a remember of the NCC (NKK?) Who said that the dutch cuber's club once had an article that ran about converting a 3x3x3 to a domino.