Hi!
Maybe this post will be useful: Steam engine modelled after a real-world kit - #27 by prisoner849
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For the uninitiated: this little wheel is part of a bicycle rear wheel gear shift mechanism:
As such, it is a variant of a roller chain sprocket, albeit on a special small scale (pitch = 1/2").
If you want to eventually animate this, I’d like to advise to be very precise with the surfaces which come into contact with other (moving) parts, like for instance the chain. The “gaps” of this jockey wheel could be modeled more generously, imo. I used a self written little .js script for the contour, while making it 3D in Blender. Maybe you’ll want to view the opening post of the above linked thread.
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You can create it from a 2D shape, an SVG or canvas drawing like, then extrude it with ExtrudeGeometry.
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Hey,
First of all…thank you very much for inspiration and ideas - very nice people Here in the Forum!
The examples you showed me - this goes definitly in the right direction allthough i have too add some more elements. Actually i am quite new in three.js and IT
seem to be easy to use but fore more.qualitity you have to have a lot of experiences.
Maybe i can geht one or two more hints …but i have to say what i want to do. I am Just doing this funny Figures from old table-soccer-balls (www.elockis.com). There i combine old bicycle stoff with the Balls and the result you can See here in the Picture. Mostly i combine the ball with a jolley and on the top i put some Material as hairs. So this ist the Basic Form and this i want to build with tree.js.
The example you send me ist yery close to thing i want to build (can i re-use the.code?) but i have no Idea how i can put a ball (spheregeometry?) directly on IT so i have the basic “elocki” -figur for using in a Game. (Eyes , nose and mouth will come later).
Oh, I see. 
I was hoping for another entry into our unofficial roller chain animation challenge. Apparently, you are not that interested in precision modeling but rather into the “fuzzy” stuff - no offense intended!
Still I recommend the “Model in Blender - export/import as glTF file - visualize in Three.js” workflow. Be aware, that both Blender and Three.js come with a learning curve, though.
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Hey, after spending a lot of time in visual Studio and studying the examples i am now a little bit futher. I got a sphere for the.corpus and some Basic geometries for the parts but now i am in a stuck state. I really spent a lot of time with the examples tree on a ball but maybe i am to stupid for the aspect of the cordinates and x,y,z Handling. ( I have no Problems with color, Material or things Like that ONLY with positioning the Elements in the surface!).
As you can se in the pictures i added i want to add ears and eyes ON the surface of the sphere but it does not work. Maybe you can give me a hint or an idea or another example - i am really frustrated now.
The eyes and parts (as a cylinder or a sphere) shall:
- sit In the surface
- shell move and Turn with the Corpus
- ears shall be exactly in the other Side
- eyes shall be in the Front …Same height but a little bit away from each other
- nose in the middle of the eyes but a little bit more in the Center
- the base exactly under the Corpus
And -this ist really important- the whole figure should Turn around the Axis around the two ears (as an table-Soccer-Figure…shurely you know what i mean. (IT IS The blue Line in the Picture)
So …any help is perfect also for only a Part of my Problems. I know IT IS a way 
Thanks krungle
