The Gates Foundation recognises the importance of condom use to world health, so my application to them for funding will be based on today’s invention.
I’ve made suggestions before based on Alan Turing’s work on pattern formation.
In order to make men keener to use condoms, they should be patterned with spots (rather than stripes).
The effect of this is an apparent visual size increase, thus greatly incentivising the use of condoms.
I hope the image effectively illustrates this comparison (although the average contrast is not exactly equal in upper and lower images).
(My attempts to use other size illusions, such as Muller-Lyer were less convincing).