The Dark Knight Sticky Bomb Gun build

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Sorry, this is seriously pic-heavy.

So I've been working on this prop since about 2011, but never made any real progress. I first started the design using SketchUp (when it was still a Google product) by looking at pictures, etc. The model wasn't great.

Later on, I got the Hot Toys The Dark Knight Rises figure that came with all kinds of props, then traded it out for The Dark Knight Armory that came with even more! And guess what - lots of Sticky Bomb Guns to refer to:

I started trying to measure the 1/6 gun (with a ruler) and copy the design into SketchUp. Even when I finished that and was ready to have it 3D-printed, I couldn't continue with the build due to crazy costs! I uploaded say just that rear handle to Shapeways to have printed - it was like $200! And that's hollowed out! So to print the whole thing (for prototyping, remember) would be like $1500-$2000. So obviously that never happened.

Fast forward to 2017 - it's my birthday and I got my first 3D printer AND a digital caliper! Yay I can do accurate measurements, refine my design, and actually print this thing!

I spent a few days re-scaling my 3D model (still just in SketchUp) with the caliper and making sure things would fit together and functionally work. Looks OK!

Then I went ahead and printed the first piece - the handle.

I have to say it turned out great. It's truly an amazing thing that we can make whatever we want – and this is what I want:

Over the next night and day, I've printed a few more pieces:



I'm noticing that each little piece I print has something that I messed up on or needs to change, so I'm really glad that it's costing only about $2 per part to prototype this!

I'm going to print the rest out and refine as I go ....

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Ok small update - I printed out more parts, but I'm thinking I'm going to have to slice them differently before sending them to the printer. I don't want to have any "weirdness" depending on what part lays against the print bed, and depending on if there are supports needed or parts that overhang, that can create some of the "weirdness".

For instance, the dovetail sections really need some support when printing and somehow I missed that memo - so had to redo this a couple times:


But I did finally get it to a place where it printed nicely and interconnects well. You can see the little hole within that dovetailed piece where I will embed magnets so that it will stay in the open or closed position - it seems to stay closed just fine without a magnet but open is a little wobbly. I definitely don't want to be opening it while suited up and a piece goes flying!

I might just do duplicate magnets so that it stays in either position instead of one or the other. I'm really using magnets all over the place for any part that needs to move and I want it to stay in position. I'm not sure if there's a better way to do it but hey that's what I'm going with.

I also need to design some way for the pieces to move and go in the "open position" but not go any further than that. Magnets help hold things in place but they won't stop something from going past where it should be. So, I will be trying to figure that one out.

I scaled this model up from the 1/6 scale Hot Toys gun and I felt like it was a little too small overall. So, I fired up The Dark Knight on the 70 inch TV and did a little measurement on the screen! I measured from Batman's belt to his shoulder and then one piece of the Sticky Bomb Gun that I could see really well. I then applied that ratio to my belt to shoulder measurement and then measured the same part of my gun, and found that it was only about 5 mm too small! Not too far off!

What sucks about that is I do want it to be the right scale, so I scaled it up to 104%. That meant I had to redo all of the magnet and pipe holes so that they would be correct. I'd already redone the pipe holes once because I realized that a 1/2" pipe is not actually 1/2"... So, doing it again.

Before I did that re-holing, I got overly excited to print out the biggest pieces. So, I printed the front piece and it came out OK - but it doesn't matter because I'm gonna have to print everything again after all my little tweaks and changes:




It continues ...
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Small update -

I've been working on my 3D-printing skills a bit because I noticed that the way I printed a lot of these pieces is going to require a LOT of post-processing work! I also didn't realize how difficult PLA is to sand -- it's pretty hard yet brittle stuff. So, I need to make sure that I'm printing each piece with as high-quality as possible.

I've printed a few different items with differing degrees of success, but believe that I've got my setup in a good place now. Just look how smooth this miniature DOJ helmet turned out!

View attachment 758221 View attachment 758222

I think that will be smooth enough, then I can finish out the rest. It's going to be fairly difficult with PLA and on big, flat surfaces, but I'll try.

The other update is that I ordered some metal rods for the gun. I didn't want to use the copper that I'd got at Home Depot, as it just doesn't look like copper in the movie. To my eyes it seems more like bronze or dirty brass. Plus they just didn't have the sizes I needed a HD, so I ordered from That's on the way.

As soon as I get those in, I'll re-measure them, take another once-over of my design, and start the long printing process. The "fast" version took about a week to print everything out, so I'm guessing this will take a month or so. Oh boy.

Now, to a question: does anyone have any measurements or idea of the actual size of this thing?

I did use a digital caliper to measure the 1/6 Hot Toys version and scaled up, and then measured against what I saw on the screen, but the whole thing still seems a bit small compared to how I'd expect it to feel. Some of that could be that they are light plastic parts rather than metal, but I'm not sure. I'd like to be sure before spending all that time printing!

Thanks for reading and for any help!


Well-Known Member
This is me - superherodiy! Apparently I can't have more than one account/username. I guess I get that, but it sucks as I also can't change my existing username (to superherodiy). Oh well. Alright, moving on.

First of all, if anyone has any suggestions on how to do something better, please do let me know! I don't have ANYONE to help me think about this thing!

So - I've been working on improving upon my design, as I really don't want this to be a static prop - I want it to be able to fold up and expand out, just like in the movie! I also want it to have a digital timer, but that is going to have to wait.

As I've mentioned in the past, most of the design relies on the use of magnets to make things stay in place where I want them. I'm not really concerned with magnets showing where they shouldn't or don't in the original because hey I like the way that magnets look!

I did receive my shipment of brass rods from and they definitely are the right size and were cut correctly as well! I made sure that after I received them, I measured them with the digital caliper and added about 1/64" extra room in all the holes for them just to make sure they would fit.

I also put together all the previously-printed parts of my prototype. I did this very quickly, I might add, using just hot glue and some wood dowels from some foam brushes I had. Even though it was assembled hastily, it is simply amazing to be able to hold this thing in my hands!
View attachment 761947

View attachment 761948
After messing around a bit more with my 3D printer to make sure I was going to have successful prints, I started the process again with the rear handle/butt, the "spinner" that attaches to that, and the first main piece that those rods extend from, and really really sanded the handle and spinner down. I didn't even know there was 2500-grit sandpaper until last week!

Now it's time to test how those rods actually move in and out of that thing. Unfortunately for me (and everyone else reading this) I am nowhere near a mechanical engineer, nor am I someone who knows what I'm doing. What I tried to do is make sure that those four holes on that big rectangular piece match up with the four holes on the "spinner" piece. I actually did a copy/paste of the face from the bigger piece and made it into the smaller piece just so they'd line up!

There was also some uncertainty around how to ensure that a) the rods fit all the way into the "box" and b) the rods didn't come all the way out of the box when I pulled on that rear handle. I think I'm either going to go with just a cotter pin on each rod, or maybe even a "plug" that I'll print that will fit (and be glued) inside the end of each rod inside the box that will prevent it from coming all the way out. Anyone have better thoughts on that? Please reply below if so!

IMG_2888.jpg IMG_2889.jpg

I also didn't want the handle to "rock" when in the open position due to not enough plastic holding the rods inside that box. So, I designed the box with about 40mm of "hole" inside the box to hold the rods in place. However I noticed that the rods don't come out enough, even though the measurement was dead on! I measured my Hot Toys version and it shows a 11.25mm distance when open. Multiplying that times 6 (since it's 1/6 scale) it comes out to 67.5mm, so that is what I planned and designed for. Unfortunately when you look at it, it just doesn't match up proportionately to the eye -- they should come out a lot more than that, like 90-95mm.

That means I need to change the width of that area holding those rods in -- I moved it down to about 11mm to give those rods enough room to come out, while still hopefully leaving enough to hold them in without rocking. I think I'm going to have to test that and see how well it works, but it seems to at least look right!

I'm going to give that first piece another print and test and see how it goes ..


Well-Known Member
I’ve mostly finished this build. I need to make a few design updates and add the LCD screen and dial - but I have to learn how to use Arduino first! But this is basically it:


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Sr Member
It came out great. Is it heavy? In the movie he wears the peices on his back, and I always thought it would be crazy heavy to run around with.

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Well-Known Member
It came out great. Is it heavy? In the movie he wears the peices on his back, and I always thought it would be crazy heavy to run around with.

It’s not really heavy, no. It’s probably a little much to stick to my belt though unless it was on with like 50lb magnets so it did NOT MOVE at all. I was thinking about making version 2 stick to my magnetic belt, but not sure because man oh man if it fell ...

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