The part is already flat on the bed — ring band up, arm and hub on the plate. No supports. 0.2 mm layers, 3 perimeters. The clearance slider is the fit knob: 0.4 mm per side suits a jar measured with calipers; go to 0.6 if you are measuring by eye or printing PETG.
The wick threads through the centre hole; the slot lets you slide a wick in sideways instead of feeding it through. The spiral arm keeps the wick centred while the wax sets, and flexes enough to pull the holder off afterwards.
The .scad download is the same model as OpenSCAD source with these sliders exposed as
customizer parameters — upload it to MakerWorld's Parametric Model Maker and they become the
customizer UI there.
Nothing is uploaded. All geometry is built in this tab.