It may not be bigger on the inside, but this Doctor Who TARDIS Backpack will look good on you and compliment your other Tardis collectibles quite nicely.
Just think of yourself as time and space and as long as this Tardis is on your back, it is traveling wherever you go. Heck, put a doctor figure inside and let him out whenever you reach your destinations. Then put him back in when you move on. It’s like a show on your back.
Only $24.50 from Amazon.