Classical guitar
In 2017-2018, Kastning again collaborated with Alistair Hay of the Irish company, Emerald Guitars, to conceive of and build the 17-string Hybrid Extended Classical guitar. This is a double-course classical guitar, with each course consisting of one nylon string and one steel string. The low sub-A or sub-B course is the only single course. It also features a Multi-scale. This is known as the Kevin Kastning Signature Series 17-string Hybrid Extended Classical guitar.