Why the weird title, why not call them "DIY Spaceship Miniatures"? Take it as a disclaimer I guess, that this technique works for me, and produces designs that I find appealing. More importantly, this technique uses a number of different materials that might be cost-prohibitive to procure solely for miniature spaceship production. The materials are however very useful for many other art or hobby projects and if you are like me and dabble in various media, then you may just have extra lying around.
The technique presented here combines a few of my older techniques and allows me to make spaceship miniatures that I can reproduce at will. The tutorial documents the creation of the ship featured in yesterday's post.
Getting right into it, the first thing is to produce a "simple pattern", which will be the general shape of the ship's upper hull. I do this by securing various shapes, typically pasta, to a piece of scrap plastic (usually from food-packaging) using CA glue. The left side of the photo below shows the simple pattern. The photo also shows that other shapes accompany the main upper-hull pattern on the plastic sheet; these additional shapes will help bulk-out the remainder of the ship (bottom and side hulls). The shapes can be glued to any flat substrate, like a piece of office paper, but using clear plastic will help during the next step. TOP TIP: use 220 grit sandpaper to roughen the scrap plastic if it is PETE (#1 recycling symbol). CA glue clings tenaciously to abraded PETE plastic but has a hard time sticking to smooth PETE.
Next, produce an impression mold by squishing polymer clay on to the simple pattern. I find the cheaper the polymer clay, the better the results. Soft, slightly sticky clay works best and I use basic white Sculpey. If the simple pattern was secured to a transparent substrate like scrap plastic, flip it over and examine all the edges of the pattern: you should be able to see where the clay is not "tight" against the pattern and make corrections. Keep adding clay until a sufficient amount is present (~2-3 cm around the pattern at the highest point) and trim to make a rectangular mold. The transparent plastic helps here as well as it can prevent you from trimming your mold too close to the pattern. Remove the clay carefully from the pattern and you'll have a nice impression mold like the one shown below in the right of the picture.
Next, use various tools to add regular shapes to the insides of the impression mold cavities. Remember that although you are making negative spaces now, the final result will be a positive protuberance. I recommend subtlety; typically I press too hard, producing exaggerated depressions (as shown below) and the final ship ends up looking "warty".
Once satisfied with the impression mold detailing, build a dam wall of polymer clay around the mold, as shown in the picture below.
The process continues with the creation of a detailed pattern cast in dental stone poured into the impression mold. Dental stone captures fine detail better than any other material I've found, with only resin being close. Dental stone however is far easier to work with than resin, especially in the later stages detailed below.
Creating a bubble-free cast for the detailed pattern requires not only a high-quality material like dental stone but also a surfactant sprayed into the impression mold and of course vigorous agitation to dislodge any bubbles in the curing plaster. I mix the dental stone by placing my estimated amount in a cup and adding water in very small increments using a spray bottle. Since I don't mix to the manufacturer's recommended ratio, I wait at least 3 hours before demolding. A bubble-free detailed pattern is shown below; note enough plaster is poured to create a ~2 cm thick base beneath the pattern.
Build a dam (I used tin foil) around the detailed pattern and fill with 10:1 silicon rubber. I've tried this technique with a "cheap" DIY rubber consisting of thinned silicone caulk but it just doesn't produce crisp enough results. Just use a good 10:1 silicone specifically designed for mold-making and you'll be much happier. Ensure enough silicone is mixed to create a 2-3 cm slab around the pattern at its highest point. If you try to save material and pour a very thin mold, the mold will likely curl up as it cures. Incidentally, the mold shown below only required 33 grams of rubber and catalyst total. Notice the air bubbles: since it's a one-part mold all of the bubbles have risen up away from the pattern and are not an issue.
Although this particular rubber (Alumilite Amazing Mold Rubber) is designed to be demolded in 4-6 hours, I typically let it sit 10-12 hours. Also, dental stone does not require any mold release with this rubber. Once the final mold is removed from the detailed pattern (see photo below), you're ready to start making multiple spaceships.
The bulk of each ship is cast from dental stone. Mix it up as before, apply the surfactant to the mold and add the plaster. Ensure it is scraped flat, as shown below, and agitated to prevent bubbles.
Once the pieces cure simply flex the mold and they'll pop out. While you'll need to handle them carefully, dental stone is vastly stronger than Plaster of Paris or even Durham's Rock-Hard Water Putty. The picture below shows the ship components fresh out of the mold before the edges are cleaned up using jeweler's files. The pieces should all lay flat. If not, the mold was poured too thin and curled while curing resulting in distorted casts. In such cases the mold has to be recreated; luckily the detailed pattern still exists.
Obviously the ship still requires quite a bit of assembly from the raw components above. As shown in the photographs below, various materials are added with CA glue to the bottom of the main body to provide bulk. The remaining cast components then get glued all over: top, bottom and sides. Paper strips wrapped around the aft end makes a convincing engine exhaust section and more pasta pieces act as fins and struts.
Once one prototype is completed, it's easy to just cast more components and build them up in the same fashion.