Covers for Mrs. Meyer's Hand Soap Bottles

I didn't start sketching in Fusion until I measured with calipers and photographed them on graph paper. Understanding the curvature of the shoulder and neck of the bottle is much easier when you can see it against a grid. The cover is a shroud: it goes on from the open bottom and hangs on the bottle's shoulder, so its inside profile has to clear the bottle at every height and never get wider going up. I modeled the bottle's shoulder as a quarter-ellipse; the cover's inner surface is the same ellipse with both axes grown by the clearance, which holds the 0.5 mm body gap closely.

I wanted a design that I could easily change for the two different bottle sizes (and new ones if they emerge). The parameter set for the model is split in two in accordance with the Fusion setup. Driving values are the parameters I measured or choose: body and neck diameters, where the shoulder starts and ends, the neck bead, the pump collar, clearances, wall thickness, rib count. Everything else — cover diameter, bore, dome semi-axes, cover height, the radius where neighboring ribs merge — is derived. Cover height is computed from the measured bottle minus a fixed bottom gap, not typed in, so it can't silently break on the next size. The 16 oz version was the test of whether I had that split correct: change the driving parameters to the second bottle, change back, and see if the restored body matched the original exactly. The swing caught two sketch-constraint defects that I didn't pick up at the 12.5 oz values.

The dome of the cover follows the bottle and goes horizontal at the neck, so during printing the ceiling needs support from inside. I wanted to print "right-side-up" so that the visible surface didn't have blemishes from supports. That meant only the narrow bottom ring of the cover would contact the build plate — that's asking for trouble with a long, tall print, and I didn't want to add a brim. An outer brim could be difficult to remove cleanly from the cover's ribs, and an inner brim, while cleaner to remove, was still a post-print cleanup task. The tall, thin support favored by most slicers also could be a weak point for adhesion or wobble.

Rather than leave all of these problems to the slicer, the design provides support as a second modeled body: a hollow column on a base disc, a 45° cone flare up to the point where the dome passes 45°, and a solid cap that sits one layer below the inner dome. Three small breakaway tabs join it to the cover's bottom edge. It prints fused to the cover as one body by those tabs. This way, the support and the model can't move relative to each other during printing, and each body's adhesion to the build plate helps keep the other in place, too, without extra brims. Cleanup is a quick clip of the three tabs where they meet the cover, a couple of back and forth pushes on the center support structure, and the support pops out. Any roughness on the inside of the top is hidden and the outside of the cover remains blemish-free. I provide the plain shell alongside for anyone who prefers auto supports or wants to experiment with the slicer.