Apparatus mixing blended composition for skin treatment

A mixer for mixing a substance in a container, comprising:

• a motor;
• a frame configured to be controlled by the motor to rotate on an axis;
• a carrier disposed at a first end of the frame and configured to hold the container;
• a counterweight disposed at a second end of the frame opposite to the carrier;
• and
• a bell crank configured to move the counterweight along the frame,
• wherein the counterweight position relative to the axis is adjustable, and
• the bell crank is configured to move the counterweight in a first direction when moved in a clockwise direction and move the counterweight in a second direction when moved in a counter-clockwise direction.