I've tried a few things to make the door look better and obscure the view. Below I used cloverleaf aluminum sheet, spray painted it black and taped it to the inside the door. It was an improvement but kept falling off the door.
$3 Front Door Update
We have a very old front door that needs to be replaced. But like many home owners, the desire to make upgrades and our budget doesn't always align. I also very much disliked that anyone at my door could easily peer inside.
I thought a metal design in black would be great but probably pricey. Then it occurred to me a floor register might fit. I priced them and really didn't want to spend nearly $50 on 3 registers especially since I wasn't sure it would work. As luck would have it, I found three very abused registers for a dollar each at the Restore.
I figured out how to get the dusty, filthy backs off, then bent them back flat and cleaned them really well.
I spray painted the registers black and spent about 15 minutes figuring out how hang them in the little windows on the door. I didn't want to glue them so that I could easily take them off to clean the windows when needed.
I used nails at the top.
and used upholstery tacks on the bottom and spray painted them black to blend in.
Here's the end product from the outside.
I use a wreath to hide the door further.
Here is what it looks like from the inside.
I had the spray paint and upholstery tacks. Not including paint dry time, I spent an hour and $3 to update my front door.
For total privacy, I cut plastic shelf liner to the size of each window, cut a slit at the top, placed a clear Command hook above the window on the inside and hung the plastic from the hook. The plastic has some rigidity but flexible enough to push inside the window frame. I put them on at night and take them off in the morning.