(Junior warbles out a muffled edition of Silent Night)
In the 1920's, through the 1940's-ish, it was assumed that if you played clarinet, you also played flute and saxophone. This was so common, that instrument cases came set up STANDARD for these three 'horns' (all three in one case).
Nowadays, most musicians play (only) one. And finding a case for the aforementioned three, is nearly impossible. Sad. So sad.
With the fingering for flute, clarinet, and sax being very, very similar AND all three reading the treble clef, it is really not that difficult to ADD one, or both, to your primary horn of choice.
HOWEVER... and this is a big HOWEVER... to achieve maximum success in becoming a doubler, it is strongly advised that one becomes VERY competent on the primary horn FIRST. For instance: start with clarinet (which I think is the most difficult of the three). Learn the embouchure requirements (hard), make the thing sound like a 'Licorice Stick' and not a dying animal (really hard), and THEN think about adding flute or sax (more fun).
So, we're talking several years into mastery, here.
Above, we have a recent photo of Junior. Junior couldn't wait to learn clarinet first and then add Everybody Else, so he took out his little mallet, some tossed-out instrument parts, buckets of Serious Musical Glue, and fashioned himself the very first Saxoclariumpet (SAX-oh-claire-ee-UMP-et) known to man.
Stunning, no?
Although I'm impressed with his mechanical skills (and the overall weird sound he gets from this thing), I'm afraid his imaginative solution falls into the category of A-Doubling-Method-That-I-Would-Highly-Discourage. Better to do it the hard way.
Then, you'll be one of those rare musicians: a Real Doubler.
Mildred