Hi guys. This is a two part post because of the number of images. This part concerns the design, while the second part will be about the building of a Megamorphix. I just thought that you may be interested in the entire process of puzzle building the way I do it.

Inspired by this post and the release of the Witeden mini 4x4x4 (11.5mm cubies) I decided to make a Megamorphix. I don't think that I have the building skills to make one from plastic sheet (and it would be very tricky because of the small cubie size) so I of course used Google SketchUp to design the extensions.

First, create a cube of edge length 11.5m. Yes, that is meters. I do the design 1000x full size to avoid some nasty quirks SU has when it tries to create very small triangles. The scaling is taken care of during the transfer to Shapeways.Next, duplicate the cubie to make a 4x4x4.Now, I define where the turning planes of the cube are, which are then going to be used to create the extension pieces.In this build I will have to truncate the 4x4x4 across the corner cubies as shown.This shows the required truncation. The center triangle forms the center piece on the four faces of the final puzzle.Using the truncated faces, I add guides which will intersect at the corners of the required tetrahedral shape. As you can see, sorting which intersections I need can be a bit awkward, but once you find one edge the rest follow easily.The finished tetrahedron, with the outline of the truncated cube shown inside.Now I add the turning planes of the 4x4x4, which will become the cutting planes through the tetrahedron, to form the extensions required.Using the planes, I cut out and isolate the extension pieces needed. In the Megamorphix, five different pieces are required. This is the large corner part (4 needed).Now I have to subtract the part of the cubie to which this piece will be attached, using the cubies I drew before.Now, this is where SU shows its weaknesses when compare to programs like Solidworks. I need to create a thin shell (I use 1mm thick) to minimise the costs of Shapeways printing. SU has no native shell tool, but you can download free Ruby plugins which add this functionality. They usually work OK on simple shapes like this, but can go horribly wrong on more complex ones. The image below shows a wireframe view of the shelled shape.I now add fillets. Again, this has to be done using a plugin, and works well for this sort of shape. But again, it can be more difficult for complex solids, which may need a lot of manual work to tidy them up.Here I have added some small holes which connect the inner and outer "shells" of the part together. These make a manifold object and allow Shapeways to extract the unused nylon powder which would otherwise be trapped inside. At this point the part should be watertight and manifold. I use a plugin called SolidInspector to check this.This is then exported to an stl file using yet another free plugin. I can now load the stl file into netfabb basic to check that everything is OK.The next part can be very frustrating. In order to get Shapeways discount, the model density must be greater than 10%. So, sometimes I have to carefully arrange the parts to maximise the packing to achieve this. As you may notice from the image below, I added the yellow sticker template to the design, which added material to the model without increasing the overall size, thus bringing the density over 10%.Now, export the whole thing to an stl file, check it again using netfabb and upload it to Shapeways (remembering to specify the units as mm!).

In part 2, I will show some pictures of the build process using the printed parts and the Witeden cube.

If this works, are you going to sell the extensions on Shapeways?

I don't see why not. But as the printed pieces need to be added to a modified 4x4x4, that may put a lot of people off buying them.

is that sketch up or sketch up pro?

It's SketchUp 8 free edition. I wish there was a Solidworks free edition

Just to clarify (as I will probably be buying this), you need to make a half truncated cube out of the 4x4 first?

-Doug

Essentially yes, but you need to do the cuts a little (1mm) deeper than the exact cuts shown in the images above. I'll explain about this in part 2.

I would definitely buy the extentions. The pictures explain everything. I have built my mastermorphix, but it is so horrid that I scrapped it for the most part. I am looking forward to part two.

Any news on when we can see part 2?

I am still waiting for the stickers from Dr. Sticker, I ordered them on 8th and they were posted on the 9th. Naughty postal service