Design Concept:

Nice holyday DIY to share with the world, so everybody can have a little fun and maybe some holiday spirit.
This will be mini and a free version.
I planned premium version with separate candles and bigger LED-option and different power options too. Premium has reliefs modified for better print quality. 0.4 Nozzle and slightly slower speed gives better result with this model.

For candle top-s use semi-transparent like on the picture, body might look nicer with less translucent filament though.

Print Settings

K1 printer, 0.6mm nozzle but details should come out better with normal 0.4mm nozzle, 1h 32min. print time, layer height is 0.22mm and lid was printed at 0.20mm but 0.22 is completely fine, 5% infill (gyroid), Hyper-PLA and CR-Silk for lid material. LED_base should be printed wider side down, all other parts should be printed as they are on picture.
For buttons I suggest smooth plate for smoother movement on final product. Only for the lid part I recommend textured plate.

No supports. Used brim for candleholder adhesion (With glue stick or some other adhesive you might not need it).
NB! You can use supports under the lid hole to make it look nicer, but there is no need battery holder will block the view anyway.

Assembly

Just push parts together, optionally you can add some glue. Candle top is very tight, so push strongly or trim sharp edge with sharp blade to ease the insertion.
You need 4 tiny switches, 4 LED bases and 4 candle tops. four 3mm LED-s, you need some wire battery holder that is 16.1mm or less wide and 28.8mm long or less, switches must be 8.6x4x4mm

Advent mini candles

0.2mm layer, 2 walls, 15% infill