She was also an inventor and designer who developed a range of products.Following the publication of an erroneous entry in the ONDB in 2016, now corrected Guppy has in recent times been incorrectly credited with the design of Isambard Kingdom Brunel's Clifton Suspension Bridge.
She designed and patented her own chain bridge in 1811 (before the announcement of the first competition for a bridge across the Avon Gorge) but this design was never realised.
Brunel’s winning design for a bridge across the Avon Gorge differed from Guppy's patent in several significant ways: it had a deck suspended from flat wrought iron bar links rather than resting on top of chains like Guppy's; and it did not feature riverbed foundations (a key component of Guppy's design) as it was constructed 75 metres above high tide where the piers were not at risk of damage from water erosion.