How well known you are to the bank matters. My grandfather was a builder and if he didn't have his checkbook on him, he would pay a subcontractor via a check written on whatever piece of scrap wood was around. The local bank had no problem with depositing it because he'd done it many times before and he had a good reputation in town.
Many of the rules and regulations have come about because writing checks became a non-local thing. You'd send off a check to pay for a magazine subscription and it'd get processed somewhere far away, like South Dakota. They don't know who you are, so like the article said - writing a check became an extension of credit, and the writer needed some verification as to their creditworthiness.
This was the late 1930's so quite long ago. Pretty much every bank now has policies that would cause them to seriously object to a roof shingle being used as a check. So not illegal - just very unlikely to be accepted.
Could you create your own paper checks? I think you can, as long as it looks/feels like a check and has all the info on it in the correct places. You don't have to use any security features to prevent check washing (but it's a good idea). You don't even need the magnetic ink, as the check will be optically scanned, with hand-processing as a fallback (they will attach a MICR correction strip).
Many of the rules and regulations have come about because writing checks became a non-local thing. You'd send off a check to pay for a magazine subscription and it'd get processed somewhere far away, like South Dakota. They don't know who you are, so like the article said - writing a check became an extension of credit, and the writer needed some verification as to their creditworthiness.