There was nothing more exciting to getting a new pair of shoes when I was younger than being able to take that empty shoe box afterwards and turn it into a playset for my Star Wars or whatever figures. Sometimes you can get very creative and have break-away doors or even use empty paper towel rolls to make a tunnel connecting to another box, etc. I used to love drawing in fake computer consoles or what ever was needed for whatever kind of "fort" it was supposed to represent.
Although some toy series did make some sort of base for figures, most of the time we were left using our own creativity. There was just something very cool about doing this.
I am sure I was not the only one who was young in the 70's to early 80's to use card board boxes in such fashion. I wish I had pictures of them now. This leaves the door open to share your shoe box toy fort memories or if you have pictures to post them--enjoy