I love making scifi models. I find the latest kits too pricey and not what I'd really like to make so I have been going on my own course for the last few years.
I signed up for a booth at my local mini maker's faire and thought I would make a new model for the event. I have always loved the ships and gear from Ridley Scott's classic film ALIEN and I decided to try the shuttlecraft Narcissus.
I use a lot of different methods to build models and props, this ship owes a lot of its appeal to clean lines and symmetry so I am leaning toward computer controlled cutting and shaping. My 3D printer is pretty small and I'd like to make this about 3' x 2' so a computer controlled router will be the tool of choice.
I find a lot of 3D models on Thingiverse and I had been learning a bit of Sketchup and spent some time in the Sketchup 3D model warehouse. I found a model of the Narcissus shuttle there that wasn't created for fabricatiing but I could work with it.
I hadn't really learned how to use the cnc router at my makerspace but I wanted to try it out on some dense insulation foam that others on the shop had used for swords and other props. The foam is sold in big sheets at hardware stores and it is around 2" thick.
I had a worker at the home supply store score the sheet at about the halfway point so I could snap it in two and get it to fit into my car (the sheets are about 8' long.)
Step 1: Having a Deadline
I work much better with a deadline, a local mini makerfaire was a good non-moving deadline. I made this image to promote my table with a work in progress shot of the shuttle. All the models and props are previous hobby projects.
Step 2: Slicing the .STL Model
The fines details in the model preview were all images attached to the model surfaces.this was fine for me since I wanted to add the little bits after the model was cut from the foam and sealed. Foam isn;t great for fine detail with these kinds of tools and I have built lots of spaceships with little parts scavenged from tank and other vehicle kits.
I opened the .stl file of the shuttle in my some slicing software called Aspire by Vetric. I used a PC for this but you might be able to find a good slicer that works on a mac too. You need to make a g-code file from the 3D model for the router. I sized my model in Aspire also by imputing the dimensions of my foam. I came up with a size that would use four, 2" horizontal slices. The yellow preview shows what material will be removed in order to make the middle section (blue is the top and bottom of the ship) so you can see if there are any problems. The software automatically fits multiple parts of the model in the material.
The router can only cut from the top and edges so parts that undercut or go in from the sides are going to get skipped
Once the g-code is saved to a USB drive you are ready to hit the cnc machine.
Step 3: CNC
Time for shoes and safety glasses. Shoes are easy to forget in Hawaii but id rather not have a sharp tool drop on my exposed feet. I used ear plugs too, routers are noisy and high pitched.
The foam sheet is mounted to a scrap board with screws at the edges. It needs to be stable during the cutting. the scrap is in case the z depth is a bit off in your set up so you don't run the router bit into your table. After setting up the starting point with the cnc software and making sure the work area is clear of obstructions. You might want to try the code out on a piece of scrap material if it you are still getting used to a cnc router, it might save a trip to the hardware store. Some router bits cut on the down stroke and some on the up stroke, they look a lot like drill bits but are they sharp on the edges and the tips are a little flatter than drill bits. I don't recall what size bit I used but it was pretty skinny.
A vacuum attachment will save a lot of clean up, my shop has a large shop vac connected to the router mount with magnets. Breathing the dust generated by the cutting cant be good for you.
I set the depth just shy of the real bottom of the sheet so the parts would stay attached on all sides, I had some trouble with a previous project when the part would suddenly be free of the rest of the material and then it would get sucked into the vacuum or move enough to jam itself into the moving bit and get ruined.
I cut the center out of the ship to make an interior but I'll leave that part out of this instructable to keep it reasonable length.
Step 4: Undercuts
I needed to cut some material away by hand in the engine area to free up the ends of the engines from the ship. I could have made another part for this by flipping the model and having the engines point up but it would have been a challenge with the material depth of only 2"
An electric/heated knife would have helped a lot with this. the engines are kind of the weak part of my finished model.
Good source photos help a lot, I had a lucky break and got a response from a cold email to the model maker of the original film version of this ship- he sent me some photos of the the model when it was being built. I'd love to share them but I had to promise not to distribute them. You can see some of the detail 'greeblies' in the first pic from the film studio and the last pic of my model, these are the little parts from tank kits. Martin Bower does have a lot of pics on his site http://www.martinbowersmodelworld.co.uk/
Step 5: Sealing and Building Up the Surface
Foam is very hard to paint if you don't seal the surface, I sealed this ship with plain old elmer's white glue plus a little water added to thin it out. it covers great with a brush or even your finger and once dried you basically have a thin layer of vinyl that hugs the surface. Once the four parts were sealed and primed with flat white paint I glued them together with silicon glue. Hot glue is my usual go-to glue but it can melt the foam. I had to clamp the edges for the silicon glue and dented a few parts, I think if you use some card stock strips to spread out the pressure you can use clamps and clothes pins and avoid leaving indentations. I ended up rebuilding the nose with some card stock to sharpen up the edges and get a slight change to the geometry. (This ship's nick name is 'Miss Piggy' due to the twin engines in the nose. The original model has a tiny decal with a bomber art version of miss piggy.)
I added a lot of tank wheels and do-dads to the recessed areas. I lucked into some free 1960s tank model parts that saved me a lot of money, model kits are expensive now. I built up some lines on the bottom of the ship with strips of foam-core. Once these additions were sealed I sprayed the whole thing with flat white paint. the windows were hand painted with metallic blue model paint.
Step 6: Final Model
That is about it. Feel free to ask for more detail if I glossed over anything.
I said I'd skip the interior but I have to share the little version of Jones the cat that my son made out of Fimo clay for me. 3D models of sleeping cats are hard to come by so I had to go old-school. the final pic is my table at the Honolulu Mini Maker Faire. The hit of the show at my table was unfinished robot parts cut from foam that kids could stick tooth picks into.
As cool as it was to get help from the original model builder via email the best thing was getting a message from a toymaker that made the retro ALIEN action figures a few years ago. He saw my progress pics on instagram (@ClumsyBlastersPix) and he totally dug that I made this to fit his figures in the same way that Kenner made the Star Wars vehicles fit the classic figures.