Wednesday, January 26, 2011

Handmade Ornaments, Or: How to Make An Engineer Happy

I was invited by a friend last Christmas to participate in an ornament swap. Basically, each person handmakes a Christmas tree ornament, and swaps it to for someone else's. I really like the idea - it's a thoughtful, cheap way to spread the holiday cheer with your friends.

Simple, right? Make an ornament, Miss Outlier.


What my friend didn't realize is that he had just given Miss Outlier - a mechanical engineer who particularly LOVES to build things - an interesting, open-ended design problem. A girl with a nearly infinite list of cool possibilities for use of machinery and materials, given the chance to design an object that had NO functional requirements except to hold itself together enough to hang on a branch.

PERFECT. See you in three days.

So while Miss Outlier was supposed to be working on her PhD thesis, and her final class project, and taking care of her dorm residents during finals, and organizing a conference - what was she doing?

Very happily puttering around in lab, daydreaming about ornament design and playing with ideas.

Should it be milled, from aluminum? Or waterjetted from something fun, like a pretty piece of scrap tile? Or maybe crafted with cabinetry joints, from cherry or oak? So many possibilities!

And then I made the mistake of bringing up the idea at the lunch table with a bunch of other MechE students. Quickly the ideas flashed around the table - what if you 3D printed it, with a captured piece inside an outer sphere? What if you made it from acrylic, and installed LEDs? Oh, how cool would it be to have LASERS!?

Woah, okay. Pull it back a notch.

In the end I had to settle on something - so I pulled up this cool website, where you can download files for 2D shapes that can be laser cut and assembled into 3D sculptures. I chose to try making this star:

I have a stockpile of acrylic plastic (the same stuff fake nails are made of) that I keep for my own projects, and since acrylic is a dream to laser cut, I decided to stick with that. I actually do have blue and other colors, but I decided to try it first with the plain clear stuff (which I have a bunch of).

Figure: Enter the laser cutter.
In the picture below, what you are looking at is the shiny silver laser cutter table, with a clear sheet of acrylic on top. You may be able to see the curvy leaf shapes that I just finished cutting out.

When I took all the pieces out, I realized two things: there were a lot of them.

And they were pretty big.

Figure: Note how the pieces take up most of my desk.

Hmm. I began to get an inkling that perhaps this might be a little large scale for an ornament... But hey, might as well put it together.



Still working....

Drat it all!

Jamming, forcing....

This is not an easy sculpture. I'm calling bad design. (Can't possibly be user error, right...?) The slots were shallow, so there wasn't much material in contact to hold the parts together (deep slots means more secure connections). And when I DID get them aligned properly, the fit was jiggly, so the whole thing wasn't stable.

So I used super glue on intermediate connections, to try to hold it together in stages. And then I had to use rubber bands to hold the intermediate stages together while THEY dried.

And then because most of it was superglued, the last connection wouldn't line up, and I broke a corner.

Figure: Assembly via rubber bands. Note white clip due to broken corner. Classy.
Bugger. And it wasn't even that pretty. And my hunch was correct - it was very large. About a 9" sphere. My one requirement is that it has to hang on a tree, and this would probably bend the poor branch!

Figure: Ornament try #1 fail.
But, I have no shortage of ideas! I wasn't ready to give up the laser cutting manufacturing method - it's quick to prototype, free to use the machine, cheap material cost, and now it's a point of pride since the first design didn't work out. I decided to go with an interlocking design this time, to eliminate the superglue debacle. And a smaller shape. I stuck with the clear acrylic, for prototyping, again since I have the most of it. Instead of a star, let's just try a snowflake...

Figure: Seriously, only 20 minutes minutes later. Awesome.
 Oh! So much better. All it took was a few simple snaps together, and I had a pretty decent looking ornament. A little plain looking, perhaps. How about the size?

Figure: Ornament try #2. Better - but now too small?

Well now I feel that next to the other one, this ornament looks almost a bit pathetic. Too small. But fortunately that's an easy fix. This one is out of 1/16" acrylic, so I can easily scale the whole thing up to 1/8" sheets. And, as a bonus, I have a lot of fun colors in 1/8" - so I can solve the plain-looking problem at the same time.

Figure: Ornament try #3.
I chose blue fluorescent acrylic, clear acrylic, and a mirror-backed acrylic as my materials.

Figure: Ornament #3, view #2, from the non-mirrored angle.
 I am pleased with the aesthetics. But how about the size?

Figure: Size check, Goldilocks edition - just right!
Perfect! I added a couple drops of superglue (not structural, I'd like to note - just for security) and called it a day!

Figure: Now THAT is a proper ornament.
So in conclusion, Miss Outlier was very pleased with her contribution to the ornament swap. Sometimes I just have to sit back and think - man, I have access to some pretty cool equipment. I mean - of COURSE I made laser cut snowflakes from .dxf files in SolidWorks. I mean, what did YOU do?

Oh wait - yours has lasers?

There's always next year... :)


  1. Cool! I am intrigued. Where can I learn to do this sort of stuff? Already have a post-grad science degree so I am not considering going to school again.


  2. I'm not quite sure what you mean - do you mean where to learn to use a laser cutter? Or how to design a snowflake? I am quite sure it won't require getting another degree either way! :) If you have access to a laser cutter, I'm sure whoever owns it can show you how to run it. As for cool project ideas, check out