When pico-projectors – pocket-sized versions of the projectors used for corporate presentations and in-home theatre setups – first appeared last year, I was dubious about their price, performance and usefulness.

They seemed the classic case of a technology looking for a market – gimmicky playthings that would fail to justify their typical $350 price-tags (£250 in the UK). But 18 months is a long time in personal technology and the latest mach­ines are much improv­ed than the original products – such as Optima’s Pico PK102 and the device that I have been testing, 3M’s Pocket Projector MPro120.