There's a running gag that the biggest obstacle to girls growing up to be engineers is representation: you'll have 99 lego construction guys to one lego businesswoman. But a lego construction guy is just a lego construction woman without hair...
[cover picture is a mock-up. Sorry, I can't print anything yet]
I used freeCAD, an as-advertised free CAD program - a particularly strong choice for spotty internet access, with an excellent Undo history.
Measure the model. In my case there were plenty of dimensions available online, and I just had to convert from metric. I started with the head diameter, added an arbitrary thickness, and created a construction circle - centered on the origin - with half that for the radius. Then I added an octagon around that, also centered on the origin, and picked any 3 sides to be tangent to the first circle. Then I set one side to be strictly vertical (or horizontal) so it won't spin, and we have our fully constrained base.
Close the sketch and use the Pad button to bring it into the third dimension; from my measurements, I decided to pad it 0.45"
Then select the top of the head and create another octagon around a circle, this time with radius 0.1
Pad that up a good 80 thou (0.08"); now flip the model over and add a sketch to the bottom, a simple circle of radius 0.202
Pocket that out of our solid with a depth of 0.375; now a minifig head could fit inside, mostly
Now put another circle in the new pocket, radius 0.096". A hexagon might grab and release better, or some sort of flexible C shape, but I don't have a 3D printer, so I haven't tested the theory.
Pocket this another 80 thou; now there's a place for the stud on top of the minifig's head to grab onto
Okay, now we have a really basic Lego helmet. You can stop here if you want, maybe paint a funny mask on it-I'm going to keep going.
Next we'll put a stud on top - so this helmet can itself wear a construction helmet, or police hat, etc. Add a circle, radius 0.096 again.
Can't remember why I changed the color here
Pad it up 80 thou
That's pretty good. Let's open it up a little so we can see the Lego face. Select the front face of the original hexagon and create another sketch.
I went with a tombstone shape, but you can do whatever you like as long as it's fully constrained. Use X to pull in eXternal geometries (like the edges of this face), so you can anchor and center your new sketch - I used diagonal construction lines and constrained them to be equal, this is a handy trick that comes up a lot.
When you're happy with the shape, close the sketch and punch it in. I figure about halfway into the helmet is safe - you probably don't want to drill all the way through the back, so about 0.2? Don't worry about the sides, we're about to fix those.
Now go to either side and sketch a profile. I'm not entirely happy with the sideburns on girl hair, but they define the ears, and that's important.
Now we punch, but instead of a dimension, let's punch Through All
Now it's looking more like hat hair; again, we could stop right here and print it, but I'm going to keep going. Let's go to the back and add a ponytail. New sketch, a centered circle of radius 0.064" (this is a reoccurring measurement - the base of a plume or a flame, roughly the size of a stud).
Pad it a few thou, I think I went 40
Now let's pocket another centered circle, radius 0.032 (another reoccurring measurement, the stem of plumes - this hair could have any number of ponytails: fire, feathers, flags, etc)
I forget the depth on this, 60 thou maybe
Now for the heck of it, let's chamfer the edge, give it a ponytail band look.
And let's not forget the ponytail - that's a similar sketch, padded arbitrarily, then take the edge and sketch a circle on that, pad it, another circle on that, pad that, and you're done. From here out it's all artistry - not freeCAD's strong suit, but with this strong geometric base you can export into a more feature-rich artistic program, like Blender (at which I am presently horrible).
Students will learn how to make a geometrically constrained base compatible with Lego Minifigs; alternately, provide the above files to art students and those students will learn how to build on an existing model without warping the original internal geometries.
Depending on the version of this project, it could either be art students who understand the Blender basics or math students who understand the FreeCad basics. (I could be sneaky and split this into two entries, but who has that kind of time)
Students will need computers onto which FreeCAD either has already been installed; unless this is the art project, in which case they'll need Blender, which is also free.
In the version where you're following How I Designed This, just follow how I designed mine. I pulled it off in a couple hours without a guide, so it can't be too hard.
In the version where art students are making something pretty out of something functional:
- Download the file smoothlegohelm.stl from this page and (optional) legoponytail.stl
- Import it into your 3D Art Program
- Draw hair on the outsides of the helm, without going above the top line or altering the insides. You may remove the ponytail if you like.
- Print your product and see how it looks. If I designed it properly and the default fits a standard minifig, the artistic helmets ought also to fit a standard minifig; and the ponytails ought to be interchangable.
For the geometric version, assessment should be based on functionality - if it works, good job.
For the artistic version: effort, vision, and preserved function are all key.