Thrilled with our success for all of half a day or so, we quickly came to the realization that because we were using sprinkles (which are square), even with a wide range of elevation options, making a smooth hemisphere with the Cupcake would be almost impossible. It’d be like trying to create a pyramid or a dome and getting a ziggurat instead.

Ziggurat!

So we began brainstorming ideas for creating half a sphere over the surface of our model in Blender, using only the Python scripts. This was problematic to say the least because a) most of Blender’s power comes from the manipulatable interface of the model itself, as well as the hotkeys. Both of which are useless when scripting; and b) There is no “create half sphere” handy hotkey period, even if we could use them. In a fit of creative delusion, frustrated hair-pulling and occasional trips to the local icecream shop, we came up with four ideas. (The last one worked, in case you were panicking on our behalf.)

Idea 1 went something like this: “If we create a whole sphere (Blender lets us do this pretty easily) and chop it in half, we’ll have half a sphere!”   Not only did we fail to find a reasonable way of removing half a sphere’s vertices, but we also realized that we’d have to fill in the bottom of what would essentially be an overturned bowl shape. That idea was crossed out. I’m sure it’s possible to do, but our fate lay along a different path etcetera etcetera.

Idea 2: “There’s this cool modifier called ‘Subsurf’! It makes things all rounded!” I’m not quite sure why this one was a flop. I think it had something to do with my tendency to form vague ideas around nifty buttons in art programs.

Idea 3: “We could create branching arcs above the x-y plane, and just fill in the shell with vertices.” See “Idea 2”.

Idea 4 (The One That Worked): “Wait! Boolean expressions! Yes!”

The gist of what we ended up doing is that we realized boolean operations on different objects are pretty simple to script. Boolean options in Blender work just as they do in logic. “And”, “or”, and “not”. We used the Difference boolean operation on a cube and a whole sphere, after positioning them so that they overlap about halfway. What this did was create a sort of ghost mesh of a half-sphere, by telling Blender “remove all of object A that intersects with object B”. (“Difference” is the only Boolean operation in Blender where it matters what order you specify the two objects). So we ended up with a hemisphere (like we wanted), because the rest of that sphere shape overlapped with the dummy cube- which we deleted afterwards.

Some domes

Now that we could create rounded surfaces wherever we wanted; the next step was to let the user specify where they wanted them, using a GUI.

We even tried loading the model onto an SD card and building from the card. The same problem occurred. The interesting thing about this is that the print would stop in a random location each time. Finally, after digging around some forums for awhile, I found a post by someone suggesting a specific combination of versions for the software and firmware to use. With a lack of anything else to try, we decided to give it a shot. This involved downgrading the current versions of the software and firmware we were using. We then, with anticipation, attempted another print and, seemingly like magic, it worked!

Here is the list of software/firmware versions that we were using when our print was successful:

ReplicatorG 009
Skeinforge 005
Motherboard firmware 1.4
Extruder firmware 1.6

[youtube width="560" height="340"]http://www.youtube.com/watch?v=D1RcMtu1UR8[/youtube]

This was very exciting.

The builders and their aptly named Victory Cupcake.  Many congrats.

After the paint had dried we began piecing together the frame of our printer. The first step was to screw the brackets onto the middle piece:

The next step was to bolt on the bottom and all the sides. The top needed to be left off in order to install the Z-stage later. Here is what the frame looks like all together:

And again: