The origin of the model coordinate system is at the upper left corner of the canvas. +x is to the right, +y is down.
The local origin of the fluid is at its center. The fluid must flow left-to-right or right-to-left.
The local origin of the laser is at the center of the trap. The laser must point up; the model does not support arbitrary orientation.
The local origin of the bead is at its center.
The local origin of the DNA strand is at the push pin location.