Build time: about 20 hours.
Inspiration: this paper model kit.
Materials:
0.25m2 of 1mm polystyrene (PS) sheet,
one 2mm acrylic glass disc with a diameter of 20cm,
three straight 80mm pieces of 3mm mold runner pole,
about 100cm2 of 1mm acrylic glass,
light gray and dark gray enamel color,
plastic cement, body putty.
Essential tools:
a paper cutter,
a big and a small circle cutter,
a ruler, compass, and set square,
a minidrill with a cutting wheel for plastics,
a cordless electric screwdriver,
a pair of goggles,
recommended: a P100 respirator mask.
This time I decided to use a precision-cut circular sheet of acrylic glass for the "hyperdrive disc". I do not have the right tools for cutting an exact circle out of a sheet, though, so I bought a prefabricated one.
Of course it did not have any mark in the center, so I used three secant segments to locate it. The lines (made with permanent marker) are only on the protective foil. The marker is quite thick, so the location is not exact, but it is good enough for my purposes.
The top side of the hull consists of two discs: one full disc and a (slightly larger) one with a smaller disc and a slice cut out (see picture). The larger disc is bent and the straight edges are connected so that it forms the surface of a truncated cone.
A large circle cutter is used to cut out the large discs. A smaller circle cutter is needed to cut out the small disc, because the smallest radius of the large cutter is still too large.
The cone surface is then glued to the other large disc, which will form the base of the truncated cone. A circle of PS sheet is attached to the base.
The circle is made from one long and narrow strip of PS and stabilized with cardboard while the glue sets. Attaching a metal ruler to the PS sheet with adhesive tape helps when cutting such long strips.
The lower part of the hull consists of two identical octagons. One of them is divided into segments and has its center cut out. I have just used a circle cutter to remove the center, because the hole will not be visible later.
The segments should actually be a bit wider so that no gaps are visible between the segments, but I decided to take the lazy way and fill the gaps with body putty. Since the energy panels will be attached right on the gaps, this hack will not be visible at all.
There is a lot of support structure inside of the lower hull. The small square parts rise the octagon segments and hence give its shape to the hull, and then there are triangles under the gaps for additional stability (and to keep the body putty from falling through).
The upper and lower hull after applying body putty and smoothing with sandpaper. There is some putty on the upper hull, too, because I made a mistake while stabilizing its shape with a heat gun (note to self: the narrow part of a cone has a smaller surface and hence warms up faster).
More body putty and drilling holes for the Lichtwerfer (ray guns). I drilled the holes with a 3mm wood drill (which is the maximum size for a minidrill), but it turns out that this is not sufficient to center the PS rods properly. See below.
While drilling the holes, a lot of scrap material fell into the hull and made noise when moving it, so I milled some holes into the bottom of the upper hull to shake that stuff out. It worked fine, but also destabilized the support structures in the hull, so I glued a patch of PS over one of the holes. Luckily, nobody will see the inside of the model when it is finished.
Turns out the 3mm holes for the Lichtwerfer rods were not large enough to align the rods properly, so I extended them with a 4mm drill in a cordless screwdriver. A small electric screwdriver looks (and feels) like rather heavy gear when used in model crafting.
In the picture you can see the first two rods attached and more body putty on the upper hull. The outer ends of the rods have been made pointy using a pencil sharpener.
You can barely see it in the picture, but the Lichtwerfer rods are supported by small triangular pieces of acrylic glass. Cutting such tiny pieces out of a sheet is not easy, because the tip tends to chip off. So I cut out more of those pieces than I needed and used the best ones. Obviously this is not a very workable method. More about that later.
The antennas on the top of the starship have a concave shape, so I used a circle cutter to construct them.
Here is the model with the antennas and all Lichtwerfer rods installed. You will have to have a look at the larger image (click on the small one) to see the antennas properly. Also: more body putty, this time on the lower hull.
Here is an "energy panel" cut from acrylic glass and the cardboard template used to put marks on the protective foil on the glass. The energy panels are even more pointed than the support structures of the Lichtwerfer rods and you need eight of them, so just cutting out lots of them and hoping for the best is not a viable option.
Normally, you can cut acrylic glass much like glass: make a cut with a knife (or glass cutter) and then bend it until it breaks. When the piece to break off is pointy, though, the forces will not be distributed evenly along the crack and the piece will fracture.
So I used a cutting wheel for plastics in my minidrill at 7,000rpm. It is important to make each cut in one go in order to make the pieces as straight as possible. The longest edge can be made in the usual way using a paper cutter – or you just use the edge of the sheet.
When cutting acrylic glass you leave the protective foil on it, because you do not want to place any markings directly on the glass. When using a cutting wheel the foil will melt and a lot of debris will fly your way. It also emits a pretty unpleasant odor.
So wearing goggles is necessary in this endeavor. I have no idea how toxic the fumes from the protective foil are, but I also used a P100 respirator. Better safe than sorry. The respirator also comes in handy when painting the model.
The lift shaft on the bottom of the lower hull is really just a minature version of the lower hull: two octagons, internal support structure, etc. Unlike the hull itself the shaft also has a lid, i.e. it is closed on the top side of the truncated pyramid. Again I used the lazy approach and lots of body putty.
Parts waiting for assembly: upper hull, lower hull, eight energy panels, and the lid of the inner lift shaft (small octagon on the top right).
Energy panels installed and lots of masking tape attached. I am using adhesive tape on the energy panels, because it sticks better than masking tape. I am using masking tape for the ring of dark gray color on the upper hull, because adhesive tape would pull off the color when removing it.
The masking tape was cut off with a circle cutter using the antenna array as its center.
Before attaching the hulls to the hyperdrive disc, the parts of the hull that face each other have to be painted.
The light gray color is a mix made from Revell glossy black, and glossy white. These are both very viscous colors, so I also added some thinner.
Centering the hyperdrive disc while the cement sets will not work, because after only a few seconds the hulls will be firmly attached. Also, doing this by visual judgement is hard.
So I attached some strips of PS sheet and measured the distance from the end of the strip to the outside of the disc, so I do not have to rely on the imprecisely located center. The rings of the hull pieces will fit exactly around these strips, so the pieces will "click" in place and be perfectly centered immediately.
I did use the center marking to cut out the inner part of the protective foil with a circle cutter.
Fitting test. Looks good.
Hulls completely painted and masking tape removed. While the energy panels look really cool, they are also pretty fragile. I accidentally broke off a piece from one of them while removing the tape. Glueing it back in place worked fine, but I will have to remember to handle this model with special care.
The finished model with the protective foil on the hyperdrive disc still attached.
I also built a display stand from massive beechwood and skewers. There are little rubber balls on the ends of the skewers so that the paint does not get damaged. The model is rather heavy due to all the support structures and the acrylic glass disc.
Here are some pictures of the finished model.