Heptane works surprisingly well as an “activator” for supergluing any plastic to any plastic. I’ve even superglued to pure teflon rod with it.
Without knowing any better, I used to buy it in these stingy little kits:
without any thought as to what it was, but to @Olias 's point above, heptane is identified by name right on the very cover of it (as you can see in the WARNING! text in the photo here). Once you know the name, you can buy it at a favorable price instead of $5 for just 0.14g of the stuff, which also tends to quickly evaporate when you uncap the pen.