How to write special set notation by hand? Does anyone know a good resource (preferably pictures) that illustrates a conventional way to write the special sets symbols, i.e. $\mathbb{N,Z,Q,R,C}$ etc., by hand?
 A: Proper technique is to use two pens held like chopsticks.  You control the distance between the two lines by varying the angle at which you hold them just as you would with a fountain pen.

A: 
Well this is the way I draw them anyway :)
A: I don't think anybody duplicates mathblackboard very exactly. I'll describe what I do.
For $\mathbb{N}$, I draw the left vertical and a diagonal as normal, then I start over drawing another diagonal parallel to the first, then finish the right vertical. I do something similar for $\mathbb{Z}$.
For $\mathbb{R}$ and $\mathbb{H}$ I write an $R$ or $H$ as normal and then just double the left vertical.
For $\mathbb{Q}$ and $\mathbb{C}$ I write a $Q$ or $C$ as normal, then add a vertical secant line close to the left side.
A: Wikipedia, W3.org (amongst many others) have lookup tables containing almost all  - if not all - Blackboard Bold / Double Strike "fontset" characters.
Each can be C&P into MS Office documents and other Windows 10 tools (MS Paint, Notepad, Sticky Notes etc),
Freely downloadable tools (e.g. Notepad++)
Social media platforms (Quora, Facebook, Reddit, etc.)
Software development IDE's: CodeBlocks, NetBeans, RStudio, Visual Studio, etc
No different from other ASCII character(s) that use U+XXXX (ALT+XXXX)

*

*https://en.wikipedia.org/wiki/Blackboard_bold

*https://www.w3.org/TR/xml-entity-names/double-struck.html

*https://blackboard.rutgers.edu/ https://www.ctan.org/pkg/blackboard

*https://i.stack.imgur.com/v5ZbY.png
Many more.
⅀, ℿ, ℽ,...
, , , ...
ℤ, ℤ⁺,, , ℕ, ℚ, including lower case: , , , , ...
