I thought patents were 20 years. At the time, in the early 2000s, I thought the HP Laserjet 4000 was a tank. Is there any reason someone would be prevented from

I thought patents were 20 years. At the time, in the early 2000s, I thought the HP Laserjet 4000 was a tank. Is there any reason someone would be prevented from replicating a circa 2003 model printer?