There is no proper instrument that is easier than any others because of different opinions, however instruments like the triangle or any other one note instruments are probably easier than any others.
Recorder probably
a piano
Whistle
drums i think!
kazoo
The Piano.
The recorder is often considered the easiest woodwind instrument to learn to play because it has a simple fingering system and is relatively easy to produce sound on.
All string instruments can be difficult to learn, but the violin may be the easiest to learn.
Easiest project would be to create a stringed instrument of some sort.
The world's best selling instrument is the harmonica, considering they are one of the easiest instruments for anyone to play.
That would have to be either the triangle or the tambourine.
Not in the least. Triangle is far simpler to play.