@Robin you say I shouldn't include you, but you've helped me with questions on kinematics, dynamics, and statics as part of this very Arduino project!!! 
I agree that you and others have been a bit annoyed by some of the mechanical questions - which is why it would be great to have the subforum for discussing them where people who don't like those questions can ignore them :D.
@dave-in-nj you were helpful previously, so I will take 10 minutes to reply to you point by point but you and I both have better things to be doing! In the future please be constructive and helpful (as you have in the past) 
NOT part of your 'arduino' project
I'm sorry that I didn't link to it explicitly, you are not the first person to ask me to talk about which project a post is part of. Here was my answer: advice on how to build a first model from a completed design. - #14 by curious48 - Project Guidance - Arduino Forum -- So, I will link to it, but in exchange PLEASE don't derail the thread to say "This is not possible!!! It will never work!!!" since I have NO questions about it at the moment, it is COMPLETELY solved, there is no NO guidance needed on that part of the project. The Arduino is used to activate solenoid based on input from a button that is in the user's reach and fix the position in place until the button is pressed again.
as for you saying your question if it is worth doing, I call Bull S-!t....
Why? Why would I give it a subject like "is it worth hand-winding a solenoid?" if I didn't want to know this? What other motivation would I possibly have except to determine if I would receive benefits. When you saw the subject line "is it worth hand-winding a solenoid" did you think this thread would have anything in it other than me asking whether it is worth hand-winding a solenoid?
You said this:
the answer from the list was that it was not worth doing
But actually the first REPLY was:
It is easy to wind solenoids. Wrap a few turns of wire around a nail and you are done.
This is actually a highly misleading reply, and it ended up confusing me. In fact I've since found out that you need thousands of turns of wire as thin as a hair to make a good solenoid, and so this was a highly misleading first reply. Rather than saying "it is easy to wind solenoid" the reply perhaps should have stated "No, for the application you have stated, just buy one".
I don't believe it's possible for me to have more clearly stated my goal with the question than: If I need an extremely tiny amount of movement, just enough to move a hair spring let's say, should I consider hand-winding a solenoid?
And the answer to that question is "No" (rather than "It is easy - wrap a few turns of wire around a nail and you're done", which was the first reply.)
So please don't rewrite history to show me doing something else or receiving a different order of responses. Your accusation that asking about whether I should do something is "mental masturbation" is completely inappropriate.
Finally, although you state that I should not hand-wind my solenoid, I have also received the following responses on another forum, all of which give extreme amounts of information:
It takes a lot of wire, and you'll want to build a machine to spin the bobbin while winding or it'll take you weeks.
I didn't know this. It's not included in this thread you'll notice.
Quite a lot, and those ones are pretty nicely engineered. You need to set them up so the piston doesn't stick to the side. Plus you need to buy the correct wire, build a core, etc.
On the other hand, it would be fun and educational.
I think it will be a project in itself to make it work right. But certainly not impossible. You need a fixed coil, and an iron shaft with magnet attached. And a way to hold them in place. And a spring return. And...
If you're just looking to learn then by all means go for it. I thought you were looking to get a pawl moving and by that standard I would buy one.
Also clearly answers my question. At the same time I had disagreements:
In my opinion you should hand wind a solenoid. Not to have something that has any benefits over buying but to see first hand what it entails. You'll loose about three fifty in the process.
And:
Unless you have a need to wind one yourself, it is cheaper and usually better quality to buy one already wound. Rarely, I have come across the need to make one myself, but that has been very rare.
And I asked what those usages were:
I've made literally hundreds (a braille output pad costs a large fortune) plus repurposed many from old laser printers, etc. The problem is making the metal frame - you need just a small "air gap" with the rest of the magnetic circuit being iron. I have an nc lathe and milling machine, so this is easier for me than for many.
Winding the spool is trivial in comparison. Mount it on a hand-drill, or electric drill, or lathe centre. Keep an even tension (via a bendy arm works) and it will almost wind itself.
Notice how this gives me huge amounts of information that is nowhere in your suggested googled searches.
Also:
Mainly for things that need a lot of power delivered. I used to make cross over networks for stereo systems before they became mainstream.
Also, antenna loading for high power transmission systems.
Wrapping electro-magnets.
Generally it is best to use pre-built, but when you get into high power stuff, often times it is cheaper to build your own.
The wire size will depend on how much current you are delivering.
You generally want to keep everything nice and neat because that makes the device more compact. It also increases the induction per unit volume. However, compact windings tend to get hotter.
Air-core inductors have uniform values across most current ranges. However, they can get quite large. Cored inductors have a higher inductance (all other things being equal) but suffer from magnetic saturation a lot sooner than air cores.
Typically, it is more efficient to wind them tight and close in layers.
You have to use magnet wire. It is coated with a varnish so the wires can be wound closer together.
This makes it clear that the practical applications where I would use it are the opposite of what I have in mind. I don't need high power delivered - I need lower power delivered.
I have done quite a few different coils, mostly for custom speaker passive x-overs and transformers. It's not hard if you have the setup already, you can use a drill and a threaded rod, the hardest part is to get all the materials, you need magnet wire, the former and poly tape.
Again detailed instructions on how people actually do this.
I'm gonna throw out some numbers out of my butt, because i don't know any of your requirements and you have a lot of variables like voltage, force, distance hold or pulse, but on 12v you could be between 1000 or 2000 turns on 32ga for something like a standard relay coil.
Useful answer to my question.
I find it interesting that the responses here have been about buying one or the machinery it takes to wind one yourself.
I'm going to approach this from a different angle: [...] you might be interested in winding your own coil. If this is the prototype stage, just find some magnet wire between 16-28 ga and put 50 wraps on your coil form (something that your armature can slide freely in but still dang close to the wire wraps). Test it out with your power source. Not enough power? Add more wraps. Too much power? Take some off. Wire gets too hot and melts? Go to a smaller size wire and add more wraps to compensate, or add a resistor inline. If the rest of your device works, NOW you can try to find a solenoid that is sized appropriately for your task.
Literally the opposite advice from everyone else.
And:
Forget the cost, you should definitely hand-wind it. When you are into building things, you should get the experience of building things. What you'll learn doing it will be worth much more than the price of a solenoid.
So I find your characterization of how I communicated my question in this thread, and the amount of other searches or looking elsewhere that I did, to be completely inappropriate.
@dave-in-nj I really welcome your feedback and advice, and I hope you'll appreciate that I took the time to address your concerns. I learned about the practicalities of what I'm doing.
This isn't something theoretical:
I am literally building the Arduino project I linked above. If the prototype works appropriately you can pledge a small amount on Indiegogo for one. I think, once this first project is completed and shipped, you will cut me more slack in asking certain practical questions around Arduino projects
Also please note that your rude reply completely shut down this thread. So, all of the information I quoted above is from elsewhere. Do you find it useful? I bet you do.
