I made a conscript once. It was a bit unique since I haven't seen any other one like it but one which is also unknown and I don't even know if that was a conscript or some old forgotten script on a piece of stone. Basically, it was written below the line (like Devanagari for example, even though back then I didn't know anything about Indic scripts), all the consonants were written as upper case letters and all the vowels as lower case but quite smaller, almost like dots and commas, but it was an alphabet, not abugida. The reason why I created it, back then, was just for fun, and that no one could read it but me.
I haven't used it for years and I'll probably never will. Once I became familiar with more and more scripts I lost the will to create my own because in my mind no script I invent will have that one thing that I find the most important thing in any script: history. My appreciation for any script is based mostly on the scripts age rather than its looks. Except East Asian scripts.
However, I do have a desire to create a script, but I have no idea how it should look like. All I know is that it should be easy to write, very practical, not too decorative. That is why I like Greek and Tolkien's Sarati. They look just perfect in my eyes.
The main reason I would create a script would be to write my journals and diaries. I mean, that is just perfect. People make so much effort to hide their diaries, they could just write it in code. I for one would even admire a person who could decipher my scripts (because if I made one it would be complex as hell). Such a person would even deserve to read it!