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Hey everyone. First time posting here on the RPF.
Bit of an Autobiography here. Did some Mandalorian cosplay back around when Disney bought Star wars, started before and ended a bit after. I really enjoyed the craft and made several full kits for myself and my wife. I am looking to expand my horizons however and work with new materials and new settings. As you can see by the title, my current plan is to create a Warhammer 40K Blood Angel cosplay.

I have been mapping things out and collating ideas for about two years now and have decided to start working on this project. Initially I wanted to do a Chaplain, but decided it would be a bit niche and possibly easy to mistake for other Chapter Chaplains. Granted I might do it in the future but for my first time venturing into 40K cosplay I figured it would be best to stick with something a touch easier than the bone armor of a Chaplain. After that I settled on doing a Jump Assault Firstborn. Then Games Workshop released the Primaris version recently. So I was torn for a while on which version to do. Then my brother and wife both, rightfully, said Primaris are here to stay while Firstborn are going the way of the dodo bird. After that I have settled on Primaris Jump Assault. My next question is where I am currently stuck.

At what scale do I build the cosplay? I have seen a number of amazing full scale Space Marine cosplays and that is honestly what I would love to shoot for but I have a few requirements on this project.
  1. Long term care for the costume needs to be easier than my previous outfits. Everything I made was much more custom and hard to put on or off or difficult to repair.
  2. Interactions are key. Cosplay needs to be as easy to interact with people as my Mandalorian outfits.
    1. Hands, head, etc, need to be moveable.
  3. If built to scale, proportions need to look "visually" correct.
    1. I am 6' tall. A lot of the Space Marine lore has them being anywhere from 7-12 feet tall in normal armor. So I am going to shoot for around 7.5 feet tall proportionally. This way I can use some painters stilts as my feet. Will still be imposing but not so tall its impossible to wear long term.
    2. At 7.5' tall, my current limbs are a bit small. I have printed a set of hands using these files as a base. Oversize Hand with Articulated Fingers. I have scaled them down to be about 6" across when completed.
This is where I have hit a snag. at such a small scale, those hands work, but its really rough with smaller rubber bands. They work but I know they wont last very long rubbing against the 3D print material. My current design works, will post some pictures later. But in order for it to satisfy Condition 1, I either need to leave the finger halves separated so I can replace the rubber bands as they eventually break, or find an alternative solution that will last longer. Currently my plan is get them assembled, mechanically secured in place so that they function and I can test them as one unit. Then I will either purchase or sew together some gloves to fit over them and see if they still work. If they do I have an interim solution found, but am seeking a better one.

If anyone has any possible solution ideas please let me know, willing to try just about anything. Including ditching these files and starting again. Below is a list of everything I have thought of or tried.
  • Small Rubber Bands (current solution, using my wife's half inch hair tie rubber bands)
  • Small Springs: deform after a number of uses.
  • Small Wire attached to spring in forearm section: in order for the finger tips to become straight the spring has to be really strong, to strong for one finger to move.
  • Small Wire attached to constant force spring: same issue as above. any "one force" solution is to difficult for one finger to use. splitting the force into each knuckle creates a very crowded piece.
  • Small elastic paracord: become deformed to easily and their elasticity at the small size needed for my scale wont work.
My next post (later tonight) will have pictures with measurements to showcase the issue a bit more.
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Here is the promised picture.
Articulated Hands Breakdown.png

  1. This is the first attempt. I tried to use thin paracord as the tendon and a spring strong enough to bring the finger to a rigid shape. Worked great! Until I attempted to pull the "curl" tendon and realized it took 3 fingers.
  2. This is my current attempt. I am using 1/4" rubber hair ties as the muscles to keep the finger extended. The tendons are 1mm multistring wire coated in nylon for smooth action and durability. This works great to be honest. But I worry about the longevity of the rubber bands rubbing on the PLA material. You can see a small 3mm hole I drilled into the wrong end of the finger, and you can just make out the black bands of the rubber bands wrapped around the joints. They are exposed on both sides, but when I put the glove over it it will be protected well enough.
  3. I am using drip feed line as a bushing with some 2" bolts as axels to give the joints movement. Works well enough, but not every hole is sized the same and this is a temporary solution. Once I get the articulation figured out 100% I plan to print tubes of the required external diameter. Their internal diameter will be small enough to accept a flat or pan head bolt. This will allow me to take them apart for servicing.
If anyone has recommendations for how to get individual muscles for each joint so the overall force required to curl the finger is manageable by the requisite finger, would appreciate it. I was thinking about trying to use torsion spring. I did look into a spiral/constant force spring, but they get costly, at least where I could search for them.
Are those the mechanical hands designed by MWiggs for his StarCraft marine way back in 2015? They look very similar.

pic for reference:
They are! His original designs are great, but a touch to big for the scale I am aiming for. In shrinking them for my design the methods he used became impractical.

I did some ball park research on actual humans who are 7.5-8 feet tall, and I found their hand dimensions to be actually similar to the average person. So I took MWiggs files, shrank them down to about 80'ish percent size, and printed them. Perfect size for the base hand. Then when I throw a glove and EVA foam armor on top, should look great.

Over the weekend I managed to create some working torsion springs to act as muscles. Once I have the time this week I was going to make a post for that update.
Managed to create some time for myself and worked on the torsion springs.

Unfortunately the concept of using them within the hole for the joining rod did not pan out. They get warped pulling them through and they are rather difficult to set at the correct tension and stay in place. As such I have pivoted to a new idea. its a more finicky and a lot less fire and forget, but in theory as with the rest of the hand pieces should be very durable for long term use.


That green box on the left side of the picture is where I am going to put my next generation of torsion spring. I did some prelim testing using the existing 0.024" OD music wire I had from my first try. The best method I found, so as to not overload a single spring, was to create two springs only a few rotations wide and place them on either half of the finger, so that each split gets its own springs. I also cut out the guide tabs to give me an easier time working with it, but I might reprint the test fingers and see if using them will help keep the springs on their relative side. My idea was to grind down the central post just enough to let me slip a single washer in between each pivot.

Regarding the pivot point, I went to my local Ace Hardware and spent some time digging around their nuts and bolts section. Thankfully they had an excellent selection of binding post bolts and I managed to get enough of the perfect lengths to have a solid mechanical solution to binding these together. Also picked up some blue thread lock to prevent them from coming apart easily during use.

Hopefully this next week is easier on my time and when the new 0.055" OD music wire comes in I can try my testing again. I found that the 0.024" OD music wire was a bit to elastic and would warp in winding them up to tension. Hoping the larger OD wire is a bit stiffer and thus requiring of less tension to provide the spring force.

Until next time folks, peace.

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