World's Smallest Molecules
26 Apr 2025If ever I had a complaint about molecule models, it's that they're too big.
With clear ambition, a flight of fancy, in one of my frequent fits of fantasy – or insanity, the jury's still out – I set out, to produce the world's.. smallest... molecules.
It's molymod, made from pins!
This project is actually from February 2019, I filmed the production but never got around to posting it. At this point I think it would be weird to stick on youtube as people would be confused by the comparative downgrade in craftsmanship. But rather than let it be forgotten forever, here's a quick overview.
I started with a box of dressmaker's pins, the type with coloured plastic heads. The glass-headed ones are slightly smaller, but those will be perfect for hydrogen.
The task was to drill holes in the plastic heads at the specific angles to form tetrahedrons. At the time I had no better equipment, so I came up with this:
The minicraft drill, which has no speed control, is shoddily clamped to the toolpost of my mini lathe. The little jacobs chuck is held in the bigger chuck in order to let us grip the tiny diameter of the pin bodies. The compound slide is used to set the angle, so we can plunge the drill bit into the pin head using the compound handwheel.
I used scraps of laser-cut plywood and cardboard to set the height of the toolpost, to get the drill bit on the centre-line. The masking tape and sharpie mark on the four-jaw chuck is my index.
A 0.5mm PCB drill was used to make the holes.
I remember what a revelation it was to use these drill bits, with the 3mm shank, compared to the other style where the shank is the same diameter as the drill. Much easier to chuck correctly.
Ideally, I could have set this up and ploughed through all the pins in no time, but the wonky setup was pretty unreliable. The lathe's construction is so poor, that as you turn the handwheel the compound rocks up and down. It's also very difficult to drill the hole without the plastic melting. To get the feedrate correct, with the fixed-speed mini drill, I had to plunge very fast.
However, the pins cost nothing so we get unlimited attempts. Soon enough, a whole pile of pins had been drilled, and once trimmed to length, we could start building molecules.
Methane at the bottom left and FDG at the top. If it wasn't yet obvious, this absurd toy was a gift for that friend of mine who works in nuclear medicine.
I'll admit, there are some usability challenges, assembling such miniscule molecules. It's incredibly fiddly to use. But on the plus side, well, it's tiny!
