The Canon SX230HS tripod mounting screw sits offset from the lens axis, presumably because there’s no way to jam the screw socket under all the machinery that retracts the lens turret. I laid out the mounting plate as a round-cornered triangle with a 1/4-20 clearance hole for the screw that holds the camera to the plate and a 1/4-20 nut sunk under the lens axis for a tripod screw. The main adapter tube supporting the microscope mount or macro lens holder glues into the shallow trench:
The barely visible trench along the back edge matches the bottom of the camera closely enough to align it against the main tube. This exploded view shows how that works:
In fact, that trench and the hole under the camera’s tripod socket come from subtracting the whole camera model from the mounting plate. I added the fully extended lens turret just for completeness; the body is no wider then necessary to carve that trench:
The Z=0 plane cuts through the top of the curved bottom shell to simplify the subtraction. The post diameter clears the 1/4-20 tripod screw and is long enough to punch through the mounting plate.
The bottom view shows the recess for the camera tripod screw head, with the support material (which blocks the hole in the picture above) removed:
It looks like this with the support plug in place:
Removing the support plug involves twisting the legs with a needle-nose pliers.
The yellow layer comes from switching colors in mid-print, but it certainly adds some much-needed contrast to the image.
The OpenSCAD code there sinks a second 1/4-20 nut that might be useful for an offset tripod mount if you need such a thing.