Unfinished prop: GM's beam spray gun

Materials:     Cardboard,

                      LD45 Plastazote foam

                      Hot glue

Time taken:  One day

So, moving away from the costume like nature of the automail arm towards props I decided to take a stab at the Beam Spray Gun from the original Mobile Suit Gundam. I've always fancied doing a full sized RX-78 Beam Rifle from the show, but due to its relatively large size and complexity I figured the humble Beam Spray Gun would be a better starting point, allowing me to get my bearings on making guns with plastazote.

The Process

So the first step was to draw up a 2D 'to scale' version in cardboard, I started by drawing a handle that'd work for my hand size and then drew everything else to scale in relation to that to ensure that the whole thing didn't look to.disproportionate.

After that using an image on my laptop I made sure that everything was as close to scale as I could make it, I made sure to straighten out all the lines and ensured consistant angles.

 

Once that was all done, I set to work cutting it out with a craft knife.

Then from this main template I set about cutting out reproductions of the centre bit. To get a proper thickness to the gun I needed to use multiple layers of Plastazote foam, I didn't cut out the 'cap' on the end or the gun's barrel as they're both hollow cone shapes and these kind of shapes can't be produced well with simple layers. I then stuck them together, two on each side of a cardboard reproduction of the first for the sake of rigidity.

This was where the first problem came in. because I was cutting around the cardboard to get my foam layers one layer at a time the layers were not identical and there were minor variations in each one. Towards the end of things I sanded these down with a dremmel, but it's almost impossible to get a consistent flat edge with four layers of foam and cardboard.

The next stage was to cut out foam to serve as the gun's main body. Although I have a 'flat' version of the gun, the actual design has it based around a cylinder. I worked the radius of the cylinder from the original cardboard's measurements and cut two pieces of foam to serve as a base for this, followed by two more which had slits cut in to reproduce 'vents' look.

Obviously the next stage was sticking these on.

At which stage another problem presents itself: One of Plastazote's attributes is that it can be thermoformed, to a degree, but this cam back around to bite me when trying to glue the body sides down. Once I'd applied the hot-glue the edges of the foam warped, leaving me with edges that are either at uneven angles to everything else or slightly indented.

Following that came the slightly smaller section of the body, this had slits cut in much like the previous bits. Similar problems were encountered as well and one mistake on my part was that as I glued one side on, it stretched slightly, leaving the slits at an angle instead of purely vertical.

Following that I made a conical tube from the foam and put a base and a lid on, attaching them to a small tube added to the back to serve as the Beam Spray Gun's E-cap. The biggest issue here is that if there is math to make a perfect cone, I don't know it. As a result my 'cap' is wonky and when stuck on throws off the shape of the gun, giving it a bent look.

A problem further compounded by the main barrel. Once again, conical tubes are hard to make from scratch and as I hadn't thermoformed the gunbarrel when I cut the slits out of the side it refused to hold its shape and splayed outwards. At this point both the E-cap and the gunbarrel point slightly downward, giving the whole thing an even worse 'bent' look.

SO. What have we all learned so far?

1. Don't underestimate the heat given off by hot glue when initially applied, or how easily thin plastazote warps when heated. perhaps a better way would have been to cut slits in the early foam 'slices' to feed a cylinder to serve as the body in to in order to ensure straight edges, adding the detailed layers later.
2. Angles are important, the skewed vent lines throw the whole thing off on the gun's body, next time, I'll take the utmost care when applying the detail layers in order to ensure that things point where they're supposed to.
3. Cones are hard and I don't think hand drawing is the way to go to make templates. I'm considering picking up a basic 3D modelling program in order to create shapes to export to a program like pepakura to allow me to create gemoetrically perfect foam pieces.

Since I took those photos I've removed the E-cap and the barrel and I'm looking at 3D modelling software. The plan is to make both pieces using the pepakura method and this time using thermoforming on the barrel to ensure it holds its shape better. Plastidip coating would also seem to be the next phase, but I've left myself a problem where the edges where the five layers come together that runs along the length of the gun are highly visible, especially the cardboard. Masking these before coating would provide a much better overall finish.

Until next time!