Austin-dude:
This topic has come up before, and I am one of the few guys here who has owned up to needing donuts and using them.
It is interesting that your friend needed them only in the woman-on-top position; this confirms my belief that, contrary to some lpsg opinion, this position is not always good for well hung guys and their partners. The vagina (they say) is shortened in this position, and that is certainly confirmed by the negative experiences we have had using it.
That said, I use donuts in any position. Sex without them is fine if I am gentle and we are both restrained, but just occasionally we want to let fling and thrust away without holding back. That is hard for a guy over a certain length, if he knows that he cannot go to full penetration safely -- or at all. Donuts came in for me when my wife began to adjust to my girth, and then (in stages) to more of my length, and it began to be possible to use a lot more force.
Our first idea (in fact my wife's) was small towels wound round the base of my cock. We also tried using pillows as buffers, but it was clumsy and awkward. One day I happened to read something somewhere about donuts. Around the same time a guy at my gym suggested I might try them. So I began a search. Like you, I could not find a source for them (this was way before the net). But I discovered after a lot of trial and error that children's rubber play rings of a certain make worked very well, and fit my girth pretty well too. I know that sounds tacky, but in the end it was all I could find that worked. Toys R Us to the rescue.
Other suggestions I have heard about since:
1. Use the soft donut type cock rings they sometimes supply with penis pumps. You might need several.
2. If your partner is a good seamstress, she could make a set of doughnuts in fabric (and fill them with good firm material, not foam; that would give too much under pressure). A set of small ones maybe an inch thick each would be much better and more flexible than one very thick one .. as you might hope to make progress over time in increasing the depth of penetration.
I think your friend should investigate these possibilities. I look pretty odd wearing mine -- maybe as if someone got lucky at a very special version of deck quoits or hoop-la on the lpsg cruise I've seen mentioned in another thread :lol: But it is worth it for the chance it gives for us to let fling. Who cares what it looks like?
It's not surprising that it is impossible to find them available commercially ... just as with really large condoms or jockstraps, only a few guys might need them. Maybe an lpsg brand could be launched.