Keep your door securely where it belongs using this intriguing spiral wedge design that uses minimal floor space! 

I saw something like this manufactured out of rubber, and thought I'd see how well it would work as a 3D printed design.  Turns out it works quite well even when just printed in PLA, but I imagine TPU would be ideal.  This is an easy print, and no supports or brim are required.  

As designed, the model is 10 cm in diameter and 4 cm tall, which should work nicely for most scenarios, but you can certainly scale it up / down if needed as well.