My dad owns an upholstery shop. He pretty much provides furniture with padding, springs, and fabric covers.
I would love to work with your dad to learn how to upholster furniture.  Recycling furniture is a growing market
It really is. Uphosterers, or trimmers as they are sometimes called, can always find business. People always need them.
It seems like I run into someone daily getting a sofa or dinning room chairs upholstered. Do you ever help him?
Sometimes I help him with the simple stuff, like seats. I'll help with the padding and cover them with either leather or just regular fabric
Have you ever help him recover any Mid Century Modern furniture? I love that period.
Mid-century modern
Mid-century modern (MCM) is the design movement in interior, product, graphic design, architecture, and urban development from roughly 1933 to 1965. The term, employed as a style descriptor as early as the mid-1950s, was reaffirmed in 1983 by Cara Greenberg in the title of her book, "Mid-Century Modern: Furniture of the 1950s" (Random House), celebrating the style that is now recognized by scholars and museums worldwide as a significant design movement.
Architecture.
Upholstery
Upholstery is the work of providing furniture, especially seats, with padding, springs, webbing, and fabric or leather covers. The word "upholstery" comes from the Middle English word "upholder", which referred to an artisan who held up their goods. The term is equally applicable to domestic, automobile, airplane and boat furniture, and can be applied to mattresses, particularly the upper layers, though these often differ significantly in design. A person who works with upholstery is called an "upholsterer".