Master molds for Star Trek Online combadges

A little over a year ago, I made a set of cold-cast metal-resin combadges from the Star Trek Online MMO video game, as part of an ongoing costuming project.

I first drew up the combadges, rank pips and backing plates in SolidWorks, painstakingly reverse-engineered from in-game screenshots and photos of a limited-edition badge that was included in Collector’s Editions of the game:

The design included recesses for neodymium magnets that would allow the badges and pips to be afixed to a costume easily without futzing around with velcro or safety pins:

Once the molds were made, I would cast “daughter” molds out of silicone rubber, which would then be used to make the final cold-cast resin badges. The silicone rubber daughters can be reused dozens of times before they get worn out, in which case I would just recast some new ones from the masters.

After a horrendously failed attempt at getting the molds 3D printed (due to the incompetence of the guy running the 3D printer), I managed to save up for a Nomad 883 Pro mill and cut the molds myself out of Renshape.

Due to the deep pockets and fine details of the badges, I invested in a small set of extra long reach endmills from Harvey Tool:

(Note to self - make a proper dust shoe)

The completed master molds, sealed with clear acrylic paint for silicone rubber casting:

Closeup of the Command Division badge master model.

The 1/64" diameter mills were extremely helpful when doing the nominally sharp inside corners of the Command star insignia:

Closeup of the 2409-style rank pips.

The two pips closest to the right actually have a slight recess cut into their front face, as they are meant to be “half-pips” for the ranks of Lieutenant Junior Grade and Lieutenant Commander (as opposed to the unrecessed “full” pips towards the back of the photo):

I’ll spare you folks the rigmarole of the entire casting process, but basically, here’s how the silicone daughter molds and final resin casts turned out:

I polished the badges and pips with #0000 Steel Wool, followed by Brasso on an old rag.

In hindsight, they might have looked a bit shinier if I had access to a buffing wheel or dremel, but I liked how the slightly satin look fits in with the more utilitarian theme of Star Trek Online than the shiny “Hilton-Hotel-in-Space” aesthetic of The Next Generation TV series.

Captain on the Bridge!

Full Album and Commentary for those interested


Nice! Great job! Looks like it was a pretty big undertaking…but oh so satisfying!

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Beautiful work!
Thanks for your post and the link to “the rigmarole of the entire casting process”!
I appreciate the effort you put into the explanation-and the product!

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A useful guide on CNC in the context of casting at:


Very cool project, thanks for showing us the steps you completed!

Thanks for the compliments, everyone!

@WillAdams - I’m familiar with that guide. In fact, that was my first go-to resource when I started looking into CNC machining.