The starting point here is a question many of us have bumped into: can you model the petaloid base on a soda bottle using plain solid operations, with no surfacing tools at all? The maker sets out to answer that, and the end result, a rendered animation of a finished blue bottle, makes a convincing case.
The workflow stays inside FreeCAD, version 20.2.3RC1. Half of a bottle profile is sketched in Sketcher using lines, arcs and constraints, then revolved in Part Design into a solid body. From there a DatumPlane is generated and offset from the body, and a Pocket cuts into the bottom base with a length of 60.000 mm and a negative taper of roughly -12 to -13 degrees. A PolarPattern then repeats that pocket five times around the central Z-axis.
Two details stand out. A triangular profile, dimensioned at 75 mm and 105 mm, is used to define the spacing between the feet, which strikes me as a tidy way to lay the geometry out. Then fillets with radii that adjust up to 7.000 mm are applied to an interior groove edge and along the exterior perimeter edges, rounding everything into a form that reads as a proper molded base.
The maker passes along one ordering tip: polar pattern the pocket before making the fillets, since that avoids unnecessary faces. The honest caveat is that this is not a one-click affair; the maker notes the tools sometimes fail and the advice is simply to persist until they work. Anyone who has wrestled a stubborn fillet will recognize that feeling, and it is refreshing to see it stated plainly alongside such a clean result.