DMSMS stands for Diminishing Manufacturing Sources and Material Shortages. It's like when you play with your favorite toy and it breaks, but you can't find another one at the store because they don't make it anymore or they don't have any left.
This also happens with bigger things like machines that people use to make things. Sometimes the machines are old or they break and there aren't any parts to fix them because the company that made them doesn't exist anymore. This makes it hard for people to keep making things that need those machines because they can't get the parts they need.
So, DMSMS is like a problem where people can't get the things they need to keep making other things because they're not being made or they're too hard to find. It's like when you can't find a certain toy or game you want to play with, it's frustrating and makes it hard for you to have fun. In the same way, DMSMS is frustrating for people who need things to make other things.