Adding ASCII art to the source code (the HTML files) may not interest people who don't look at source code. The source code is an easy place to add ASCII art because those files open in plain text, no formatting or fancy fonts. So, the ASCII art shows up without much extra work, almost none in fact. If you access your HTML files you can add ASCII art yourself, without the plugins. (See above). But, not everyone wants to do that.
I looked at 3 plugins to add ASCII art to your WordPress blog. This is the first one I loaded up and experimented with. It does work but may not be the results you wanted. There are no options to add the ASCII art to the bottom of your posts or pages. The plugin does place ASCII art at the very bottom of my site, under the footer. Below is my first experiment. I was pretty neutral with the results. But, I'm a bit traditional when it comes to the font I use. The spacing was out, the lines between text. Also, the top line of my art was pushed to the left. I tried another ASCII, thinking a longer image would look better either way. Adding HTML code worked to keep the formatting but, it shows up on the site. Still it is nice to have a little surprise for anyone who reads to the end. So I will keep this plugin and see how often I remember to change out the ASCII art images.
Quoted from my answer on Quora:
I open Notepad (on a Windows PC) and start working on an idea. It's like a puzzle to fit the characters together in a way that creates an image. Some inspiration comes from searching for images or those I find. I look for clean lines so it will be easier to adjust when I need to figure out the spaces, characters, slopes for lines, and so on. The font you work with makes a difference. Notepad uses FixedSys (or one of the newer offshoots). I seldom like how ASCII art looks when it is shown in another font. Courier and others use a thinner line which makes the ASCII art seem washed out. Plus, even though they are monospaced, the lines in columns don't match up exactly the same. I know some people would make a pattern or sketch and tape it to their monitor. So the ASCII art would be like filling in the lines (connecting the dots). I've never done that. Most often I have a general idea and add some characters, sit back a bit and see how things are shaping up as I go along. Don't delete a bunch of stuff and start over too often. Sometimes just adding a bit of detail will pull the whole image together. Circles and curves are one of the hardest things to work with, especially if you make a smaller ASCII art image. Close lines, like trying to make fingers for a hand, are pretty much impossible unless you make a bigger image or settle for a hand with just three fingers. I avoid hands and just have people holding things. This works well cause it adds more details to the image and explains what it was meant to be. I don't use any alt characters. ASCII isn't about anything but the standard keyboard characters. You can do a lot with lines and dashes but I find a way to use numbers and letters too. It seems a bit bare without them.via - What is the process of making ASCII art? - Quora.
via - Humans TXT: We Are People, Not Machines. - Word Grrls
via - Claddagh Ring With or Without a stone by Ricksonjewellery. I like this update on the Claddagh design. I wanted to make a Claddagh with ASCII art and may use the hands in this way. Much easier than showing all the fingers (hard to get narrow lines that close together unless I make the Claddagh in a pretty large size). I found a crown on another Claddagh which I like too, a vintage ring I posted to Pinterest.