Flameless candle adapter

Most candle holders are designed for wax candles. Flameless candles don't conform to the inside of these candle holders and since the batteries are inserted from the bottom, you can't use some caulking or silicone sealant to hold them upright.

This simple print helps 20mm LED candles stay nicely vertical on many different candle holders.

Best printed from clear or white material to appear less conspicuous. The ring is pushed over the candle from the bottom (you may have to remove the screw cap battery cover) and then you push the candle into the holder to set the correct height.

These rings are tight so if your rings are too tight, scale up by 1%. I found the side against the print bed has some squish which had to be removed using a deburring tool. The chamfer is supposed to remove this but it will depend on your printer.

You can, of course, print them slightly larger so that they’re loose, then glue them to the candle holde. This way you support the plastic LED candle at two points to hold it vertical.

The ring has a short vertical cylindrical section with a chamfer, this is to fit into the top of the candle holder but if the hole is too tight, you will have to position the ring with the cylinder up instead of down. 

The ring flexes quite a bit as you fit it to the candle and holder so I suggest using PETG, PLA+ or some more flexible filament. Regular PLA is quite brittle and prone to cracking when flexed.