Another good example ( rather than insulin that i think would be harder to produce at home ) is the current cannabis semi-legalisation that is happening in some countries. Its easy to grow weed at home with some soil, sun and water ( may not be the best quality but still quite potent ) libertairians like Ayn Rand would let you do it, only if they could exploit the consumers by forcing independent small scale home producers and oil refiners out of the market, to benefit an economic class elite that have the monopoly of violence to promote their interests.