A commercial play-kitchen for school age children (ages 5-10) would have cost our child care center close to $900 USD. An assemble-it-yourself (full-size) cabinet-with-hutch cost $300. By printing some of the parts, and buying a few other cheap pieces (e.g. the faucet cost about $35), we could make a play kitchen for less than $400 USD.

The inspiration for the gas burner grate came from JFM3D at https://cults3d.com/en/3d-model/game/bruleur-gaz
That model was way too tiny, and I needed mounting holes so I could bolt the burners down to the "stove top." So I designed a burner from scratch in FreeCAD. This burner is roughly 125 mm in diameter and has an M6 threaded hole under each foot. I used only two of the holes for mounting.

The knob is a remix of @ThatNaysayer's Kenmore Gas Range Burner Knob (https://www.thingiverse.com/thing:5023793). That knob is a replacement part for an actual working stove. I trimmed off the stem, made the knob solid, and added an M6 mounting hole underneath. When mounting, I placed a washer between the "stove top" and the knob, and tightened the bolt just snug enough that the knob still turns with some resistance.

I used painted-on supports on the burner. I only supported the middle-third of the overhang, and allowed bridging on each end (see screenshot above). This made separation a snap (pretty much literally). The .bgcode file will print one of each, a knob and a burner.