I bought a bunch of plastic frames, enough for three complete hives with two mediums each. My bees are the same, they hate to build on it. I tried spraying and then drying the sugar water. I placed the plastic cells between two wood frames - that seemes to work, but I think I caused a swarm in two of them because the bees probably felt crowded. I do not like the plastic frames at all.
When it one day does get drawn out, I for sure will not scrape and crush and strain. I will keep these in the bottom brood chamber forever if possible. Or I will use them for nucs or for swarms captures.