[hnnmzh]

Some additional thoughts.

With some training, people can read seal script inscriptions because the structure is already fairly close to regular script which is what people use today.

The radicals are written in slightly different styles from today. It actually makes sense. Seal script is a very artistic form of calligraphy, so people use it for their seals hence the name.

An example of the "drum" character: http://www.guoxuedashi.com/zixing/yanbian/11208mb/ The horizontal arrow is the time line, starting from oracle bone script. The 4th one of the first row is seal script and the last regular script.

The idea depicted here is hitting a decorated drum on a rack with a drum stick holding in the hand.