LED holder for the second generation (i.e. MK2) modular lamp created by Trusted Developments. https://makerworld.com/en/models/834175-modular-lantern-new-core-tops-and-skirts#profileId-779100 

Instead of buying a $13 puck light, and spend hours printing a diffuser, you can obtain a cheap LED flexible strip light (around $6) and attach it to this mount. Light is emitted horizontally to fully illuminate the decorative plates. You will need a 3.3' (1 meter) long self-adhesive LED strip for this. I provide step by step instructions for installing the strip onto the model, and for installing into the base of Trusted Development's modular lamp. 

Another advantage of this design is that it's easily moved between different lamps - Just twist and it's free. The light and cylinder are all one piece. So, if Halloween is over, you can just move the light cylinder over into your Thanksgiving lamp. Ditto for Christmas and so on. You don't really need the light fixture sitting around in lamps you won't use for another year.  

Do be careful when removing the unit from a lamp. When turning the cylinder counter-clockwise, be sure you don't pinch the LED Power cord.

Latest updates:  I've added arrows showing where to insert the LED strip. I've added an arrow to the first and last retainer arch.  I've also added a slot at the top of the cylinder - so you can insert the last bit of the strip in order to hold it more securely. I still recommend sealing the deal with some silicon adhesive at the very end (at the slot) per the instructions.