This follow up to Mad Monster Party (1967) is actually something of a prequel, telling the story of how Dr. Frankenstein made the mate for his original monster. It was produced as an installment in The ABC Saturday Superstar Movie series.
This was released on DVD shortly after it's predecessor was. Above is a clip from the film, uploaded to YouTube by buster2k8.
Obscurity factor: 8 (largely forgotten, available on DVD and in part on YouTube)