Reverse Engineer the FALLOUT - Lucy's Tranquilizer Dart Gun in Fusion 360

This project describes the steps I took to recreate the Tranquilzer gun Lucy uses in Fallout. The fun I get from a project like this is to first make something not readily available in a store, make it myself from scratch, improve my Fusion 360 CAD skills, make it look screen accurate as possible, AND acutally fits together for realism. There is an intrinsic reward in taking this reverse engineering to a higher level and making it as accurate as possible than to say - "close enough." So if you want to learn how to transform a photo to a real live prop, follow along and let's make Lucy's gun!

1. Subscription to Fusion 360 or similar CAD software - or buy the STL files online already made. Go here if you don't wish to design it from scratch: FALLOUT Lucys Penumatic Tranquilizer Gun Darts Kit 3D model 3D printable | CGTrader
2. FDM Filament for a 3D printer (takes approximately 1/3 of a roll). I reccommend ABS+ for ease in sanding, but PLA prints much easier but needs more finishing time.
3. Super Glue (CA), or fast setting epoxy or similar plastic adhesive.
4. Rustoleum Spray Paint - 1 can Black Auto Primer, and 1 can Hammered Silver Metal (good looking gun finish).
5. 1/2 Dram Sample bottles from Amazon (be sure they fit the dimensions shown or they won't fin into the dart body. 1st Choice Glass Vials, 1 Dram, Pack of 12: Science Lab Sample Vials: Amazon.com: Industrial & Scientific
6. Food dye for the water in the Vials
7. 3M Spot Putty or wood filler, sandpaper, files, exacto knife etc. for cleaning up your 3D prints.
8. Acetone or MEK for rubbing down your ABS parts only - NOT NEEDED if you are using PLA filament.

GRAB SCREENSHOTS: Obtain as many pictures as possible of the items you want to recreate. Ideally you want all the views possible you can find. Side, front, back, top, and bottom views would be heaven to get all of those. Mostly, you will be lucky to get two of those views and they will be blurry when you grab a screen shot or two. Often, it is easier to watch the movie live action, pause and take some screen shots, but then take notes what you saw. The paused picture will be blurrier than what your eye can actually pick up.

ONLINE PHOTOS: If possible google search for movie "stills" or photos. Sometimes there is a movie still online that will show the item very well. If you look at my other instructables, you will see 2001 - A Space Odyssey that had many movie still photos during its production that helped me tremendously, yet even those pictures were actually in conflict with each other because the movie used different versions of the space suits during filming!

ESTIMATE OVERALL DIMENSIONS: Once you have your photos, try to get overall dimensions (L x W x H) to define how large it really is. Don't just start drawing and then later after hours you discover it is way too big! Look at other things in the photo that you do know how big they are, and compare the two. Example if the item is laying on a table next to a soda can, you can measure a can at home, and estimate that the item is "two soda cans long" etc.

COMPARE TO REAL ITEMS YOU HAVE ACCESS TO: If you are drawing up a ficticious gun as in this case, is there a toy gun available to get those dimensions as a starting point? These initial sizing steps are crucial to getting the scale right the first time. Many 3D drawings of such ficticious items are typically drawn way too big and have to be scaled down in 3D printing step which may create a ton of wasted materials, AND TIME to get it dialed in.

To get the size of the dart correctly, I start from the inside out, with the dimensions of the vial, to be certain it fits in the body so I drew the vial first and then the dart body, cap and end cap around it.

REVERSE ENGINEER TO GET DIMENSIONS THROUGH RATIOS: Sometimes there just isn't a good basis from which to reference dimensions from an acutal object you have directly in front of you. The object you want to draw is so unique there isn't anything at the ready to compare it to BUT if something in your reference photo may have some reference, then ratio off of that. For example, see the 2001 Jet pack photo. I didn't have a jet pack laying around so ... I could see in the movie still it is about as long as his mid shoulder blade to the center of his hips, so I had someone measure mine and used that dimension for the length, then ratio'd the width to the length off of that photo. try to do this only on straight on photos so the parallax doesn't throw off your accuracy.

OK, Now we can import those best photos into Fusion as a "Canvass" to TRACE over. Ideally, if the item is not symmetric like the flying saucer in the photo, it is best to get photos in each view and add them to your origin in Fusion for each of the 3 planes to draw from. See photos.

Once in Fusion 360. then I have the reference photos from which I can draw the object from and keep it in scale to the height, length, and width.

Fusion 360 is a VERY powerful drawing platform which is fairly easy to learn. There are many helpful tutorials online that can get you started. The more you practice drawing the better you will become, just stick to it and try different approaches to drawing the object if you get stuck. Some simple tips are:

1. Use the canvass to trace from in the front on view, and use top and side views as guides to ensure you stay within the overall size of the object..
2. Think of how the individual "parts" would be made if you were actually making it from a solid piece of wood for example.
3. Extrude into sub shapes. Cut out solid areas that are not needed.
4. Anchor your drawing with dimensions back to the origin so that changes to dimensions can be easily made.
5. Save finishing touches like champfers for the last steps.

Once you have a part firmly designed, be sure to only have the one part visible, then click on file, export, and choose stl. This will save that part as a stl file that your 3d printer slicing software can understand.

Now run your 3D software (Cura as one example) and open that stl file in that software. Set up all your printing setpoint settings to match the filament type you will use. Pay particular attention to the orientation of the parts as some will print at a way higher quality than in other orientations and also may minimize support material clean up. These two issues are sometimes not in support of each other. I sometimes get a cleaner part if reorientated than those where support structues are minimized. Note the dart photo... I used a tree method because a standard zig zag support just wasn't supporting the thin walls of the dart good enough.

This step by far is where your project will make or break it as to how it will finally look in quality. Several other of my instructables talk about this step, and I encourage you to read some of those for very detailed instructions, especially for large parts that need bonding stronger than just glue. The basics are as follows:

Clean up as much support material as possible with exacto knives, files, and sandpaper. Trim as much of it off as possible with a knife because sanding will take forever. A good file works wonders here in rough clean up.

Then sand the parts with increasingly fine sandpaper. I go down to about 220 max, and then look for parts with layer lines and other defects that I will spot bondo and resand. I repeat bondo and sanding multiple times until i get the smooth surface I want. Eventually I get to about 400 and call it quits there if I want a very clean surface.

i then follow it up with SANDABLE auto primer which has a lot of filler in the paint to get the last bit of layer lines hidden. Painting then sanding then painting again will show exactly where the high and low spots need to be addressed. When done with this step a final primer coat it sprayed on so the piece is uniform in material for the final finish coat to bond strongly to and not flake or chip off later.

If my prop has a lot of parts to it I will finish and paint each part first, then scrape off the paint where I need to apply glue so I have true plastic to plastic for the glue to bond together on each piece. Then i will assemble them with clamps, rubberbands, or tape until the glue is firmly set. I will then follow up ith touch up of an entire spray coat of final paint for an overall finished look. If I choose to weather the item ith a mud wash or similar I often follow that up with a matt clear coat to seal everything in.

Just be sure to use the same manufacturer's paints so as to not invite compatibility issues between paint products.

i hope this was helpful and you have some new approaches to modelling unique props. Please visit the other instructables I wrote up to see more on specific tecniques in fabricating 3D printed items.