Make an adapter for a AAA battery so that it works like a AA battery.
1) You need to increase the size of the AAA cylinder as well as make it removable so to put in a fresh AAA when needed. Cut a 3/4 X 3 inch piece of paper. Roll the paper around the AAA tightly and then roll 19 inches of 3/4 inch electrical tape on top of the paper.
2) Make a second cylinder...
3) Get tin foil and make a 3/8 inch ball of it so that it fits in one side of the cylinder you made. Put the AAA battery in the cylinder and crush the tin foil down flat. That will make the
AAA 3/16 inch longer than it is so that it is now 1 15/16 inch long
the same size as a AA battery.

Step 1: The 3/8 Ball of Tin Foil

Cut a piece of tin foil 1x4 inch and ball it tightly by rolling the piece between your hands. It should fit into any end of the cylinder, then insert the AAA and crush the tin foil ball down till
the AAA is the same size as a AA as shown.

Step 2: In a Working Device

Now you see 2) adapted AAA's in a CD player that uses 2)AA batteries. It works fine, won't play as long as 2) AA's would. I will guess it plays only about half as long.