Molotow Chrome Pens and 3D-printed Holder

It's my birthday today, but in a twist, I'm going to give you a present! This is a 3D-printable pen holder that I designed to hold 4mm Molotow Pens. Why do you need these pens, or a holder for them? Mirror-chrome! Both paintable and airbrushable. The holder I designed allows you to keep the pen upright and opened without worry about spilling. Since these pens need to be kept upright once you crack the tip, this holder can also be used for storage.




















Design

I used a pair of calipers to take measurements of the pen to design this holder. It's composed of 4 key parts:

1. The base has a 65mm diameter, plenty to fit the other parts and ensure nothing will tip over.
2. The pen holder in the center fits the 4mm case perfectly, including an offset at the bottom where the pen steps in for the lid.
3. A cap holder (displayed below on the right) which lets you firmly snap the unscrewed lid in place.
4. A curved section (displayed below on the left) where the inner section of the pen can lay without worry of it rolling away and making a mess.

I build the design of this holder using OpenSCAD, a free programming based #D design software.

I've made this STL available to download freely from Thingiverse, though attribution is required for spreading and it's not to be used for commercial purposes.

I'd be happy to design holders for their other sizes of pens and refills if someone wants to send me to free swag to design from! :D

Opening The Pen

1. Instead of pulling the cap off, unscrew the whole lid section. (Place it on the holder.)
2. Use a knife to pry up the plastic inner section that seals off the reservoir. (Lay it on the holder)

WARNING!

There are 2 parts you could potentially pry open. The one you want shares a diameter with the body of the pen. There's another section slightly indented that's under pressure of a spring and wet with paint - if you pry it open, you'll slingshot chrome splatters across the room. (Luckily, this happened outside and I was able to clean it up.)

Painting with the Ink

Application

The ink will dry with a finish similar to what it looks like when it's wet. If you apply it like you might apply a regular paint, it'll look more like silver than a mirror. It needs to be applied thick.

This means painting with a brush can be a little blobby, unless you're filling something in like a small cockpit, goggles, a decoration, maybe a weapon you can thickly apply to... basically, it'll look good, but be ready to lose some detail. (Although even the fine canopy lines on my X-Wing miniatures weren't lost, so it's not THAT thick, just thick for someone used to thinning their paints * grin * )

You can run it through an airbrush without any additional thinner. It's the right consistency to use at standard pressures. (16-20 psi) Since you'll be spraying thick to get the right chrome look, be sure to fully mask the area you're airbrushing to avoid overspray!

You'll need to wait hours for it to dry and if you touch it out of curiosity, you'll ruin the finish. I usually don't assume it's ready for a day.

Washing Over Chrome

The finish of the chrome is super glossy and thin paint like washes beads up, so it doesn't apply very well. It also appears to cloud the chrome. At most you could carefully paint washes into recesses and force darker shadows.

Painting Over Chrome

Using this for my X-Wing cockpits, I needed to paint the canopy back in after chroming them. To do so, I first painted the canopy using Liquitex Black Gesso. (Paint on primer) If I thinned the gesso at all, it beaded on the surface of the chrome, so you need to apply it normal and thick. But this does allow you to paint over it.




Varnishing

Varnish clouds the chrome. There are apparently some clear coats out there that work and I've had a little luck with Liquitex Gloss Varnish, but you'll definitely want to experiment first. Unfortunately, NOT varnishing makes it susceptible to tarnishing by touching. So be warned.

Also, as mentioned with washes, thin paints, including varnish, will bead on the surface of the chrome and not apply evenly.


Clean Up

I've been using Tamiya Lacquer Thinner for cleaning both brushes and airbrushes. It's nasty stuff - you don't want to be breathing it in without a mask at least.. and use in a well ventilated space. But you REALLY don't want the liquid chrome drying in your airbrush or the base of your brush.