user15533: I have a project made with Arduino, and I want to replace it by a miniaturized circuit with just a microcontroller. Is there any tutorial that can guide me in doing this? Any reference is wellcome. Thank you!

user19504: The main question is: Which features do you want to have on your board?
You can start off with the design files of the Arduino board you are using: update what you need (and don't need). 
Then, for the manufacturing itself, several approaches will work:

veroboard & through hole components. Not very practical, not small, but easy;
DIY manufacturing: toner transfer method, or if you have a CNC, isolation milling;
Boardhouse (e.g. PCB manufacturer) to whom you send your finished design to have it manufactured.

An alternative would be to use a smaller board, like an Arduino nano: it all depends on what your constraints/goals are.

user4664: You can use an Arduino on a breadboard to get you going. From the breadboard, you can then develop a circuit on a pre-made PCB like this:

Then to a custom PCB, if you so desire.

15533: <p>I have a project made with Arduino, and I want to replace it by a miniaturized circuit with just a microcontroller. Is there any tutorial that can guide me in doing this? Any reference is wellcome. Thank you!</p>
 19504: <p>The main question is: Which features do you want to have on your board?</p>

<p>You can start off with the design files of the Arduino board you are using: update what you need (and don't need). </p>

<p>Then, for the manufacturing itself, several approaches will work:</p>

<ul>
<li>veroboard &amp; through hole components. Not very practical, not small, but easy;</li>
<li>DIY manufacturing: toner transfer method, or if you have a CNC, isolation milling;</li>
<li>Boardhouse (e.g. PCB manufacturer) to whom you send your finished design to have it manufactured.</li>
</ul>

<p>An alternative would be to use a smaller board, like an Arduino nano: it all depends on what your constraints/goals are.</p>
 4664: <p>You can use an <a href="https://www.arduino.cc/en/Main/Standalone" rel="nofollow noreferrer">Arduino on a breadboard</a> to get you going. From the breadboard, you can then develop a circuit on a pre-made PCB like this:</p>

<p><a href="https://i.stack.imgur.com/gl4zM.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/gl4zM.jpg" alt="PCB"></a></p>

<p>Then to a custom PCB, if you so desire.</p>
