Well, Paul and I got together and made a truckload of more clear parts, and - I don't know what I was thinking when I saved all those squeeze-bottles, but - we found that
none of the condiment- or dish soap squeeze bottle-stock worked, at all. Invariably quite thick - which may have been the whole problem right there - all those pieces might also have just been the wrong type of plastic. Don Czech had earlier theorized that curved plastic stock was "pre-programmed" to deform/curl up when heated, but Paul and I noted exactly the same for
completely flat sections - only from these type of (thick-plastic) bottles.
In contrast, the "Good Stuff" - typically from tool- and similar vacu-packaging, being about half as thick as the squeeze-bottle plastic - will actually flatten/open
more when (re-)heated, becoming noticeably clearer and shinier at the same time. But the real key, which you can only truly know when holding the piece as it's heated, is that it becomes "looser" and distinctly rubbery. As opposed to the "Wrong Stuff", which tightens - pulls back on you - while curling up, and more often than not begins to cloud over, as well. Some other (even thin plastic) pieces were found to "frost over" when heated - a very interesting effect, but not what I was after. Finally, even some of the Good Stuff yellowed noticeably (it seemed) if slightly, at the moment it was heated - though that may have been my fault, holding it too close to the heat gun.
Paul and I tried to identify these classes of plastic from their recycling labels, but so far no definitive findings (which will probably require some serious note-taking). When I
do figure it out, though, you will be the first to know.
Meanwhile, fortunately I had saved up a
lot of scraps, of all types of clear plastic - and we employed every useable one, to make 63 parts, of a full dozen types:
Click on Image to EnlargeFully 5 of these types - 2 kinds of turret domes, 2 types of antenna dome and a bombardier's window - are for refitting my PB4Y-2 Privateer, although of course the spares will serve any- and every future build that can use them. Copies of another 1/72 scale bombardier panel will fit a late-model B-24 Liberator. And a 1/48 scale extended windshield of the FJ-3 Fury (right background) will also be useable for the F-86 Sabre from which it was derived, as well as no doubt many another '50s/'60s-era cockpit canopy, too. Among the easiest/most reliable parts to form, these windshields and (very similar) bombardier panels came out perfect (or nearly so) on 100% of "pulls", while more dome-like parts would come out flawless typically only 75- down to 25% of the time.
The
most difficult - and surprisingly, as it was such a simple, rounded cone shape - was the nose dome of a Heinkel He-111 (left foreground), tried no less than 13 times, in pursuit of at least one perfect example:

That perfect "pull" never was achieved - the forwardmost 1/3 to 1/2 formed perfectly just about every (92% of the) time, but further back a pleat and/or tear would inevitably form at some spot(s). The problem may have been insufficiently-large pieces of plastic stock, for pulling over such a large/long form, to begin with - a part like this needs a good 6"x6" sheet of plastic, I estimate. Nevertheless, the above 13 pulls did produce 3 with completely flawless port sides (left, foreground) and - after noticing this and deliberately rotating the armature 180 degrees for subsequent tries - another 3 were pulled with flawless starboard sides (right, foreground). So, fully three of these can be assembled from (carefully trimmed and mated) halves - and no doubt several others using more fractional panels (if it were ever necessary).
OK, so I was wrong about being able to use condiment squeeze bottles (but still, don't forget to get the extra
food out of them). The above however - if anything - shows just what you can do with all kinds of other saved clear plastic scrap - just wait till you see my He-111 torpedo bomber!
Cheers,
-Matty