This is another remix of Kirbs' Flexi Rex, based on airfish's remix. That model in turn was most likely inspired by the Flexy Rex by zheng3.
My print of Kirbs' model was not very kid-proof: one of the links broke after some rough handling. Hence I made all links more robust. This means this model can probably be printed even smaller than the original ones before the links become too weak. Of course you can also scale it up at will.
If you want to make a dual extrusion print like this one from Adafruit, check out the remix by AndrewSink.
If you want to create your own flexible model, make sure to check the Hinge Design section below.
Note to anyone wanting to sell this: this model is released under a Creative Commons - Attribution - Share Alike license. The details can be found here but in a nutshell it means you are pretty much free to do anything with it including selling prints if you comply with the following conditions:
- ‘Attribution’ means you must always provide a visible reference to the origin of the model both on the webpage where you sell the model, and inside the packaging of the actual physical product. A link to this page or even just “Thingiverse thing:2738211” suffices. You should also, and perhaps in the first place, refer to the original model from Kirbs (thing:1759297). A ready-to-print attribution card is included with the downloadable files for this model in PDF format. I don't care how the attribution message is formatted as long as there is no possibility that anyone could believe you are the author of the model because you are selling it. This is a very easy requirement that doesn't incur any extra cost except a minute of your time. You do not need to share any profits¹. If you skip this tiny simple effort and catch enough attention, it might end up costing much more than you gained from it.
- ‘Share Alike’ means that if you make modifications to the 3D model and sell or give away prints based on that modified model, you must publish this modified 3D model. Easiest is to click the ‘Remix it’ button at the top of this page to publish your modified model on Thingiverse. Make sure to set the license to Share Alike (or something more restrictive, but not less). Again, this costs you nothing except a few minutes of your time.
If you see this being sold anywhere without the required attribution, don't bother notifying me about it unless it goes far beyond the small scale of a typical Etsy or Facebook store. I don't have the time or means to hunt down all the unscrupulous people who want to make it seem as if they created this model and sell it at an exaggerated price. Moreover my contribution to this design is relatively small: Kirbs deserves most of the credit. If you do want to spread awareness about this model's true origin on sites where it is sold without attribution, post a comment there and link to this page if possible.
This model contains about 70 cents worth of material when printed in a premium filament. Add to this the costs of electricity and perhaps depreciation of printing infrastructure, and you might end up with $2 at most. Anyone who pays much more than that for a print is being ripped off.
(1: Of course you can always use the “Tip designer” button if you really want to share some profits or just want to show some appreciation.)
No supports needed. I used 3 perimeters to ensure the hinges are strong, this is much preferred over trying to obtain strength through infill. If you use too high infill, the model may become poorly balanced due to the head being too heavy. If you want to improve stability, use a higher infill for the piece with the legs if you can.
This should move freely right after you take it off the build plate. If you print with hairspray on a glass bed, the Rex should spontaneously jump into a random pose all by itself when it pops off the plate after cooling down. If you need to use force to free the hinges, you still have some optimization work to do on your printing technique.
This is not a demanding print. If this is one of the first things you're printing and it fails, expect other things to fail as well.
If you want to create your own flexible model, by all means copy the hinge design from this one, or at least use the below image as a guideline. I see way too many ‘flexi’ models that still use the weak hinge design from the original model, or other shapes that have way too little material in the most crucial locations, often the end of the shackle or ‘ring’ is too thin. Make sure to provide as much material around the axle hole as possible, instead of cutting away as much as possible, as some designers tend to do. You won't gain any flexibility by providing more clearance than needed, the model will only become weaker.