How to mold precise rubber parts with sugru

sugru user Carson created this fantastic project, showing how he moulded a precise new strain relief for his cable using a 3D printed mould.

"A clumsy seat-mate on an airplane broke the audio plug on my earphones when he was trying to get out of his seat. I was able to remove the existing overmolded strain relief and resolder the connections, but I was left without a strain relief. I used some heat shrink tubing for a while, but was unsatisfied with the appearance.

Here's how he did it:

1) I used 3D CAD software to model up the strain relief geometry for the audio plug. 2) Using the original CAD as reference, I then created CAD for a 2-sided mold for the part.

3) I printed the mold parts out in a 3D printer (polyjet). 4) Needed some mold-release chemicals to allow the parts to come out of the mold, like greasing a cupcake tin. Didn't have any mold-release handy so I used olive oil. 5) Mold the Sugru around the bare audio plug by hand, while properly aligninge plug into the mold. 6) Close the mold with a C-Clamp and remove excess squeezed out of the mold. 7) 30hrs later, Done! Open the mold and enjoy the new overmolded strain relief I created!"

This is the most precise part we've seen someone make with sugru so far, and we're looking forward to sharing with our friends at Makerbot and the Thingiverse community.

Super inspiring!

Your comment

Please register or log in first to ask a question

Register or
Please wait…

Other people's comments

And could you please tell me which 3D CAD software did you use? Cause I would like to create moulds as well.

Thanks for the article! It was great. Lot's of good information, and it helps with my research I am doing for custom rubber molding

Any chance we're gonna see this on Thingiverse? I'd love to print one..

Hi Mikael, that process will work for you. With compression moulds, you don't need to leave the mould on while the sugru cures. Use soapy water as a release agent (It's the best) compress then release. You can also repeatedly compress until you get the finish you want. Would love you to share your project on gurus when you do this -

  • James
  • James

LOL- looks great but i believe the 3D print must have cost a hunded quid or more- hardly seems worth it but i guess money isn't everything?

  • John P
  • John P

I just ordered some Sugru and went to this blog. This 3D printer mold i kinda cool, but I wonder If one'd be able to make a mold from Sugru, say by dipping an existing strain relief in some sort of mold release agent and forming a Sugru mold around it. Then, the day after, cut the mold in two halves, fill 'em with Sugru, put the wire in the middle, press the two halves together (maybe using a rubber band to keep it tight overnight) and hey presto - a molded strain relief!?

  • Mikael
  • Mikael

[...] an interesting project. Carson shares how to make precise pieces from sugru using a 3d printed mold.  Most sugru repairs I’ve seen are of the “blobby gooey” kind. This one looks [...]

Yep we agree, this project is a total 'wow'. Not neccessarily for this particular use, but the opening up of possibilities that it creates. We can't wait to see more ways people combine 3d printing molds and sugru. @marcello sorry to hear you weren't able to get a nice looking finish when you did this repair by hand - I guess it depends on what you think looks good or not, and there are some tricks to making it smooth and even. For most people who still want to repair these by hand we've made a step by step here to show how

  • Jane
  • Jane

I bought sugru specifically do try and do the exact same thing. Only i did it by hand. And it sucked. BIG TIME.

I ended up ripping the sugru away because it looked really ugly...

you're my new hero!!! :D


WOW!! Not having one of those wonderfl 3d printers - has anyone done this a manual way - like with a casting compound of some kind using some existing physical model (another plug?).
Wouldn't that make a nice Instructable.

Nice, but overkill for this, I think. You can do a good strain relief on a cable by simply using Sugru and carefully moulding it by hand. It holds well.

As a precision moulding system, using silicone sealant would work out cheaper, since you don't need the ability to touch it, as Sugru allows, and the same release agent would work. It is also lower viscosity, so easier to compress the mould.

DIY and crafting have been taken to a new level!

  • Carla D'Anna
  • Carla D'Anna

I love this... I hope we see more molds created with 3D printing that we can then use to make parts out of other material, like sugru. :)

Wow. ... That is some serious technology expertise! ... I'd love to know how to make molds like that. The written steps make it seem easy! ROFL

  • Sue-on-the-farm
  • Sue-on-the-farm


  • Brett
  • Brett