How to make adjustable dual +12V & -12V TO +30 & -30V

They are probably all from the same manufacturer with multiple brand names stamped on them as is typical from china. Which is why when looking for chinesium devices I like to cut the middleman's profit out and buy direct from china. Usually on AliX or fleaBay. Long delivery but can cut the price substantially down. Hard to beat most Amazon prices but not for china manufactured goods if you are willing to wait on the slow boat from china for delivery. FWIW