After the failure of the SMK during the Russo-Finnish War (a.k.a. the Winter War), the similar T-100 was re-evaluated and several designs were proposed to be built on the chassis, after it was partially dismantled. The only design that went anywhere was the T-100Y, which mounted a 130mm naval cannon in a fixed casemate. Since it was no longer a tank, the name SU-100Y was also used at the time, and that is the name it is most commonly known by. The SU-100Y was used in the defense of Moscow, however all reports claim that the Germans never actually got close enough to be within firing range of this beast.
The SU-100Y is the subject of my very first CAD tutorial, which you can view here:
Be warned, however, if you want to know exactly how to make one yourself, you will have to sit through 3.5 hours of some of my worst work.