Casting Scenery Pieces with Hirst Arts Molds

March 24 2019

Taking a break from code for a bit, I thought it would be fun to document another project; this Christmas I found myself finally biting the bullet and picking up some of the amazing terrain molds from Hirst Arts.

I've enjoyed the hobby of collecting & painting miniatures like those from Games Workshop's games, but scenery building was always something that felt like a step beyond what I was comfortable with, with complex tools and materials, larger workspace requirements, and a whole lot of requisite skill in art, design, architecture, outdoor layout, and more that always scared me off. Of course, I've watched everything I can find on YouTube over the years about the topic, and have turned to 3D printing in the past to make little odds and ends, but it never met my minimum quality bar.

3D-printed barrels

I recently found some truly stunning 3D-printable pieces designed for Space Hulk, but my old Cube just isn't up to the task anymore, so I gave up. However, the particular YouTube rabbit hole that '3D Space Hulk' brought me down reintroduced me to the idea of casting dungeon tiles in plaster, and everything I watched seemed to lead back to the work of one company, Hirst Arts.

Hirst Arts

Hirst Arts molds are the product of a single person, Bruce Hirst, who has run this company with his wife for nearly two decades. It's hard to overstate just how much effort has gone into it: over 150 different molds, all sculpted by hand, with incredibly detailed casting, assembly and painting guides and videos. If you're even slightly intrigued by the hobby, take a deep dive into the site and YouTube channel.


Daunting at first, now after tons of research I was pretty confident that I could handle a project like this, but I still needed a few things to get started:

Dental plaster, or dental stone, was the only thing on my list that I really had no clue where to start with; none of the common dental stones used in the Hirst Arts-based projects I could find around the web were available here in Ireland, but I did find a supplier that seemed to have all the right things. The identical bag designs did nothing to help me choose, so I picked the one just cheaper than the most expensive πŸ˜‚ Dentstone KD it was.

Various plasters

Dental stone is a type of very-hard plaster that's often used in dentistry to make models; it sets quickly, and doesn't chip easily if dropped on a hard surface. It comes as a powder, and, if you add a little water, in 15 mins it turns to a very ceramic-like material. I could, of course, use a common, cheap plaster like plaster of Paris, but anything I made with it would be far more brittle β€” dental stone is a must for some of the thinner, more delicate mold pieces.

The arrival

25kg (55lbs) of plaster is a lot more awkward than I was expecting it to be; when the delivery person arrived at the doorstep with the bag in hand, he was baffled as to why he was delivering this to a home and not a business (πŸ˜…). I had figured that I could just keep the plaster in the bag it came in, but it was very clear that wasn't going to work, so I had to add something else to my shopping list:

One trip to my local DIY store later and I had a pair of 22L sealable boxes that were perfect. Now that I had everything I needed, it was time to drum up the courage to get messy.

First casts

Starting simple, with a Space Hulk/40K/Kill Team theme in mind, I had picked up a bunch of scifi-themed molds. I knew I would need more at a later date, but this seemed like a broad selection that could go a long way towards building the interior of some space ship. Click through some of the links to get a preview of the pieces that come on these particular molds.

Mold Name
Mold 276 Large Catwalk Mold
Mold 278 Large Deck Mold
Mold 279 Large Grate Accessory Mold
Mold 302 Cargo Bay Accessory Mold
Mold 325 Industrial Edge Mold
Mold 327 Machinery Builder Mold

I started with 276 and 325 as the basic building blocks β€” floor tiles, a door, and some edge pieces β€” and figured I could go from there.

I won't lay out the steps to prepare the molds, mix the plaster, pour, scrape & demold because Hirst's site has documented this in so much detail, but seeing the first pieces come out of the mold made me incredibly excited. They were ceramic cookies of such precisely-detailed terrain tiles far beyond anything I could hope for from most 3D printers. All the Americans on Twitter informed me that it looked like I was making waffles; I am not so familiar with your dietary customs so I defer to your judgment πŸ™ƒ.

First cast pieces

The quality of the sculpts blew my mind, and it turns out the Dentstone KD I chose at random is perfect for high-quality, durable pieces. Each little piece is akin to a Lego block, but I could make them ad infinitum with just some plaster and water. With enough casts, I could have enough pieces to build a city. With a whopping twenty-five kilos of dental stone, I sure had enough material to build a city.

Side pieces

With a couple of casts, I started being able to piece together small sections of terrain β€” tiny sci-fi themed rooms, that were at the perfect scale for 28mm miniature games like Warhammer 40K or D&D. It was starting to become clear that this had every sign of becoming a very dangerous lifelong hobby; I was now the dental stone god, and I was bringing forth creations from dust and water…


Tiles arranged into a small room with a door

And time. And a lot of time. Boy is it time-consuming to cast your own Lego blocks before building the things you want to build. Each cast takes about twenty minutes to set to a comfortable hardness (though I double that for delicate pieces), even if I could do several molds in parallel. But, nevertheless, the possibilities were blossoming before me.

Piecing together scenery

Three days later…

A table full of pieces

A couple of days in, and I was amassing a mountain of pieces. I had seen some magnificent work on a similar project online, and I set myself to aping as much of it as possible. These designs, pretty as they may be, take a lot of pieces to pull off. Even the simplest corridor section needed as many as 30 pieces to build up the walls, and many of these particular pieces existed only as single pieces on one mold. Accelerating this was going to involve a rabbit hole into making my own silicone molds, but that's for a future post.

Granted, building the most elaborate scifi set I could find was always going to be much, much more intensive than building a simple dungeon out of fieldstone pieces. Slowly but surely, I built my spaceship interior section by section, room by room.

The beginnings of a spaceship

There's more to the story to come, but I'm very happy with how this is turning out. It may take years to finish to any reasonable level of completion β€” I'm leaving the painting of all this to poor future me β€” but for now I have what I think is the makings of a gorgeous, incredibly visceral game board for 40K-based games.

I can't recommend Hirst Arts molds enough; browsing the hundreds of available fantasy molds while watching Critical Role and trying to figure out what to order in my next batch is my new favorite thing. I know I'll never have enough of them, but it pays to have a creative hobby that brings you joy. Between this and Raspberry Pi, it certainly makes my YouTube recommendations way more fun πŸ™ƒ.