Mount Everest is the tallest mountain by elevation above sea level, but the tallest mountain by total height from base to summit is, when the undersea portion is considered, Mauna Kea in Hawaii. (howtogeek.com)
The first piece 408 - foot - tall spire (which will bring total height -LSB-...] (downtownexpress.com)
Total height once put together: 42 cm. (amazon.co.uk)