1/72 Soviet Heavy Tank T-100Z

Keep in mind that its not exactly a "paper tank". It was developed because the Winter War reveal that 76 mm gun is not enough to fight heavy fortifications, so new main turret with 152 mm gun was developed and it was planed to be put on the place of the 76 mm gun turret. The 152 mm turret was produced but at that T-100 project was abandoned it was used on fortification around Leningrad. so its not "paper tank" it just wasn't assembled.