The ghost trap has always been my favourite piece of Ghostbusting gear. Therefore, I thought I would post my own build here too. I am based in the UK, and when it comes to the finishing of 3D prints, many build threads tend to mention materials only available in the US, so I thought it may be useful to others by documenting the methods that work well for me.
I'm going all out and will be building the 'mega-deluxe' version of Sean's kit. This includes all additional hardware and the Arduino based electronics to provide lights, sound and smoke. However, I plan to make a few customisations to make the trap behave more like it does in GB1:
- MULTICOLOUR LEDs: The original design includes three bright white LEDs for the main lighting with a purple lighting gel for colour, but I would like to be able to adjust the colour and brightness so as to simulate some of the effects seen in the movie.
- CODE EDITS: I'd like the trap to behave like it does in the Sedgewick Hotel scenes as operated by Ray, so a few code adjustments will be needed.
- MORE ACCURATE SFX: Sean includes edited versions of the sound effects from the video game, but I'm not the biggest fan of them and would rather it sounds like it does in GB1. I can't seem to find them anywhere and I think isolating them well from the movie would be near impossible, so I'll have a go at recreating them as accurately as I can.
Right, 'nuff talk. Let's get to it....
First off, I'm printing all the parts in black PLA. For those in the UK, I've had good general results with Amz3d and Sunlu filaments available on Amazon. As I'll be smoothing and painting almost every part, no need to be fancy here and waste time with high resolution. Sean also provides a useful print guide which mentions the parts that require greater infill or a slower print. Otherwise, a standard 0.2mm layer height with a 0.4mm nozzle does the job beautifully:
Next comes the bit that (literally) stinks. Just because this is a 3D print, doesn't mean the final prop has to look like it's made of plastic. That's what I really dislike about the Matty traps - just all shiny and cheapo looking even though it's not all that cheapo. I want to get rid of all the layer lines and print marks, but the only way to do that satisfactorily is to use automotive body filler. Most prop making forums and videos talk about using 'Bondo' to smooth out printed surfaces - specifically Glazing & Spot Putty that can be used straight out of the tube. This is something we can't get in the UK, so the closest is Isopon P.38 Body Filler. Unfortunately, it's a two-part filler meaning you have to mix it yourself with separate hardener - this makes a messy job even messier, plus the fumes this stuff kicks out is enough to get you high as a kite. That may sound like fun, but the smell is as nasty as the paste is icky. In this case though, it's a necessary evil, so let's smear it all over everything we need to smooth out. Isopon provide an application tool, but it's tiny and generally useless, so I find it easiest to wear latex gloves and use my fingers to make sure the whole surface is covered:
I could have been a bit more careful with these parts and applied the filler a bit thinner, but you don't get long before the P.38 starts hardening and we're gonna sand the s**t out of everything anyway. Once everything is covered and left about 30mins to set, the sanding marathon begins. And nobody likes sanding. Not even prop makers. But it has to be done, so I soldiered on by dry sanding the surfaces back down to the plastic with 150 grit sandpaper. This is no fun whatsoever - especially around corners and crevices, but if you persist, you'll end up with much smoother surfaces with all the low spots evened out. This is what I like to call the 'Friesian Cow Stage':
Time to moo-ve on (see what I did there?) to the primers. You hear a lot of recommendations for Rust-Oleum Filler Primer, but this is another product not found in then UK. Instead, Halfords do a really good line of automotive primers which work really well with print finishing too:
First up, I gave everything a coat of the Filler Primer (in the photo is a smaller can of their Plastic Filler Primer, but I have found their regular Filler Primer works identically in this case and you can get it in larger 500ml cans for only £1 more). It comes in a delightfully putrid orangey yellow colour but sprays on incredibly smoothly and touch dries in 10-15 minutes:
As with the P.38 body filler, I sanded this back down to the base level (sanding wet this time with 400 grit). Even though it's touch dry in 10 mins or so, I leave about an hour before sanding. The colour of the filler primer provides a very helpful contrast between the black PLA and the white P.38, so you can clearly see the small areas it is filling. This is the point all the sanding scratches and print lines are starting to be filled. It may look a mess in but the surfaces now feel very soft and smooth and the patterns created look like they are printed on. I call this the 'Tiger King Stage':
Next, I sprayed a second coat of the yellow filler primer and an hour later repeated the previous step (again wet sanding with 400 grit paper), only this time leaving much more of the primer on the part. This simply removes any roughness and feels more like a gentle scrub. We then end up with each part being super smooth - you can see where all the layer lines, print marks and sanding scratches are, but they are now undetectable by touch alone when running your finger over them:
Finally, everything gets hit with a coat of Halfords standard Grey Primer. Once dry, I just rub everything down lightly with some kitchen roll. For all those absorbent towel geeks out there - Regina Blitz is the shitz. This gets rid of any surface dust that may have embedded itself in the primer when spraying and makes everything as smooth as possible, ready for painting. All layer lines, seams and other print lines are completely gone and the parts no longer feel plasticy as they did straight after printing.
That's all for now. Stay tuned for the next exciting episode where I literally watch paint dry...