Protopipe - Spectrum 3847

We have been working on creating a system to allow us to quickly and easily design mechanisms that let us prototype game tasks.

What we have come up with is called “Protopipe”. It’s an inexpensive system that lets you 3D print connectors for 1/2" PVC to easily build prototypes, test them, and iterate them. We haven’t run it through a season yet so there is almost certainly room for improvement but we thought other teams might like to use it as well.

Blog Post:

Explanation and Notes:

3D Files:

GIFs of the prototypes



This is really cool! Reminds me of the “Chaos Tower” toys I had as a kid. Anticipating where and how to build adjust-ability into prototypes was always a weak point in processes I lead – will definitely consider this in the future if working with a team with ample 3d printer access!

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This looks awesome, thanks so much for sharing this. I can’t wait to give it a try, I could really change how we approach prototyping.

Really cool! I can see how these will make prototype iteration faster.

What have you found to be the advantages of working with PVC vs. 2x4s or aluminum tube (other than cost for that last) for prototyping?

Anyone ever design a system (including some sliding elements for adjustability) like this for 2x4 prototyping?

We didn’t add a table of contents but we did address this at the bottom of the document.

Why we didn’t choose other options
2x4s or other lumber

  • Prototyping with wood works but making bearings or slides, etc. takes a long time and you have to manually lay it out and drill the holes, etc. 2x4s are often to large for a lot of tasks. Cutting them requires using the miter saw (chop saw) which is more difficult than a simple manual PVC cutter and harder for new students to use. We will still use them for certain things but the pipe is much lighter and faster to work with.
  • Wooden Prototype Examples -

VEX Versatube or 1x1 aluminum

  • Versatube is great but it’s not affordable for a lot of fast prototypes. Also you can’t just snap things on to versastube, pivots and shafts are also harder.

REV extrusion or 80/20

  • Added benefit of being able to add things in the middle and slide certain things over versatube but definitely more expensive and harder to cut to size than the ½” PVC pipe.

Answered in the document, mainly being the larger sizes were challenging to fit everything in. You likely could do 1x1s (or other sizes) if you want, and would have to fitting out a conversion.

And interesting stuff. Now just sell a standard kit of protopipe fittings (after a year of testing, i guess). Also, how many pieces of each fitting did you find you needed (or which ones were most popular)?

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We won’t be selling anything, the whole point is it’s cheap to make yourself.

For your second question, that depends on the application, look at the examples we provided to see which connectors were used the most in each one. The corner joint is useful as it can be used to connect 2 or 3 pipes so we printed the most of those so far.

4159 worked on a similar system involving tube connectors (Aluminum not 3d printed) over the summer and the start of this year. We had to abandon the project due to time constraints but I really think a lot of the work we did could be converted to your system using 3D printed parts.

This was one of my favorite parts that we worked on.

It will allow 2 tubes to freely pivot between an angle you could set. It uses a shoulder bolt and some CNC milled parts that could be replaced with 3d printed stuff. One interesting application would be the intakes like the madtown design from this year.

Other stuff we worked on/had ideas about:
2 way/3 way fixed connectors
2 way fixed connectors that you could adjust the angle of
Linear/Rotational Motion
Elevator Rigging
More stuff I’m forgetting

I would love to help you guys continue this project and build it into something even larger. I’ve always thought that more could be done in the area of low cost, rapid prototyping. If you want any CAD files or an explanation of things I’ve mentioned please lmk.

4159 also worked on a tube based prototyping system over the summer/during the fall but unfortunately, the project was abandoned due to time constraints.

One of my favorite concepts we came up with was the idea of a tube connector that could pivot between 2 angles that you can adjust using a shoulder screw.

Pictures v

Other concepts include

-Adjustable fixed angle connectors
-2,3 & 4 way 90-degree connectors
-Bushing based sliders
-Cascade/Continuous Elevator rigging
-Adjustable angle connectors that are also bearing mounts
-Hex inserts for the rollers
-More stuff I’m forgetting off the top of my head

We still have all the CAD files and although our system was made for metal I’m sure it can be converted to 3D printable designs. Would you guys be interested in some sort of a collaboration? 4159 would love to help with this project! I can provide CAD files/explanation for our designs as well.

I’m not exactly sure what type of collaboration you are looking for. The entire system is open source, so you are more than welcome to use and modify the system and if you would like publish changes or additional parts, feel free to post links to any additions in this thread.

This is very similar to industrial building systems like Creform or Fast Tube, but it’s scaled down to a more practical size for FRC and is within the means of most teams costwise. Nice work!

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FWIW, similar pieces are available commercially. I noticed “saddle tees” at Lowe’s yesterday when shopping for stanchion materials.


Very cool system. Thank you for sharing. How many, of each type, would you attempt to have on hand at the start of the season?

There are too many variables for me to even wager a guess. Different games and different teams will need different resources.

We will be updating this with some new items this fall.


I’ve been printing out as many Protopipe connectors as possible to prepare for build season and to test out my 3D printing pipeline capabilities. Also the 5254 HYPE blocks.

Every team would benefit from using these in some way and if you’re just prototyping with them, may as well be printing them now so you have them week 1 of build season.


That kid without safety glasses eye level next to those flywheels…get that man some glasses!

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Are those (or anybody else’s Protopipe prints) in PLA, and if so, what kind of success did you have? The document says to use PETG, Nylon, or Polycarbonate to print these, I assume because they have to flex to snap around PVC and PLA is quite stiff.

PLA+/PLApro works well. Standard PLA snaps pretty easily but if that is all you have they can work for certain applications.

We don’t have anything yet, but are trying to decide between MatterHackers PRO series PLA and MatterHackers Tough PLA. From what I can tell, Tough PLA has a lower flexural modulus and higher impact resistance, which I would assume would mean it does better in this application (this is based on Ultimaker datasheets because it seems that MatterHackers doesn’t have their own datasheets for tough PLA).

This is the PLA we use, almost everything printed on our robot was printed in it this year including our pneumatic tire hubs and more.