If you are not using foundations in your hive (e.g. top bar or - as I do - frames without foundations) there is a fair chance that you are using some kind of starter strip. Most commonly this would be a simple line of wax (works well in my experience, but can be a pain to apply), made of wood or a strip cut from a wax foundation.

An advantage of using foundations is actually that they give you a certain amount of influence on what size the actual cells will be. Seems that 5.3 - 5.4 mm is a very common cell size (measured across 10 cells, so this includes walls) used for commercial foundations. However, some beekeepers claim that this is way too big and has a negative impact on bee health (mainly varroa) and they therefore started to reduce cell sizes on their foundations to <5 mm.

Basically when you let the bees build their own honeycomb, they are likely to build what is best for them (which most of the time will be smaller than 5.xx mm). The problem is, if they come from an e.g. 5.3 mm cell size they re likely to build similarly large cells.

So here my attempt on trying to combine the advantages from both worlds (so yes, this is rather experimental). Give them a size to start with and likely they will continue to build the same size. I have included started strips in 4.9, 5.0, 5.1, and 5.2 mm for you to chose from. Some folks claim that you have to slowly reduce the size (I currently use 5.0 mm). They are all 220 mm wide (I know, this is not the full width of your frames but likely they will start in the middle and will continue building to the sides) and single sided (it seems the bees don't care and it really helps with the print). This is because I wanted something that is really easy (single print) and fast (approx. 30 mins/piece) to print. I simply cut a groove or slit in the top bar of the frames and hot glue the strips in.

Also in my experience you don't need to dip them into hot wax (not such a good idea with PLA anyway). What I do is I use a piece of cold wax to rub over the surface of the starter strip. Seems to work (see the picture after 24 hrs).

Hope your bees like it. Here is a collection of some of my Beekeeping Designs on Thingiverse.

I hope this works for you (so far it does for me). However, remember, this is somewhat experimental. So please share your experiences!

Enjoy!