I have a pretty small car, because of that I'm really limited on my storage options. But I use my car often, both for work and for fun. Usually I find myself putting whatever is in my hands onto the passenger seat and usually by the time I get where I'm going this stuff finds its way onto the floor, between the seat cushions or stuck between the seat and the door. It also makes my car messy and I have to spend a minute or two moving things out of the way if anyone plans on sitting in the passenger seat.

I came up with a way to make a securely fastened box that will never slide or fall over but that can be easily removed with all its contents and put into the back seat or onto the floor if I need room for passengers. It works by buckling directly into the unused passenger seatbelt.There's no reason this can't buckle into the back seat too when needed. In addition, I decided to make the box adjustable so that it can be placed either horizontally or vertically on the seat for more options.

Step 1: Materials

You will need:

- A storage container

- A piece of plastic/PVC/ etc. the same thickness as the metal on your seat belt buckles. I used polypropylene.

- A drill

- A marker

- A Dremel tool or hot knife ( I tried both. Go with the Dremel if you have the option)

- A bolt with a matching nut. (Use butterfly nuts if you want more options)

- Calipers or a ruler

- Heat Gun (optional)

Step 2: Measure, Buy, Trace, and Cut

Measure the thickness of the metal on your seat belt buckle. This is how you'll determine the thickness of the plastic you need. Get a plastic sheet of the same thickness. I found 1'x1' sheets of polypropylene at my local Grainger for $1 each. You'll really only need about half of that, maybe less.

Using a marker, trace the shape of your seat belt onto the plastic and cut it out using a Dremel or other rotary tool. I tried a hacksaw, a knife, and a hot knife. The hacksaw just didn't work and neither did the knife. The hot knife worked but it was slow and smelled terrible. I imagine the fumes are pretty bad for you too. Don't forget to mark and cut the hole on the inside or it wont buckle properly.

Once everything is cut out try to buckle it. Mine didn't fit the first time I tried. Turns out I needed to make the hole in the middle a little larger. After the second try it fit great!

Step 3: Line Everything Up

Once you have your plastic buckle working properly you will need to place your storage container on the seat in the spot where you want it to rest. Line everything up and mark where you want to make the cut. I decided to allow my storage container to fit in either direction.

Now it's time to cut your plastic buckle to the right angle. I had to do this twice to get it just right. The first time was a little off so I cut it a little shorter for minor adjustments. I also ended up needing to cut a notch because my storage container had little plastic ribs near the top edge that were in the way. I could have cut those but I decided to notch my plastic instead.

Step 4: Bend and Drill

When lining everything up I ran into a small problem. I have bucket seats so my storage container couldn't sit right up against the belt buckle. I needed to bend the plastic to make it reach the container.

An easy way to do this is to pinch your plastic in a vice, heat it with a heat gun and bend it to the approximate angle you want. It's pretty flexible so don't worry about getting it exact. If you don't have a vice you can pinch the plastic between 2 pieces of wood for the same effect.

Once you have the right angle going, dry fit everything and mark where you want to drill. Drill a hole that matches the size of bolt you will be using.

Again, I decided to drill 2 different holes in mine so I could change the orientation of the box if needed.

Step 5: Bolt It

Connect your plastic buckle with your box by attaching the nut. Using a butterfly nut will make it easier if you decide you want yours to be switchable like mine.

Here you can see the box set up in 2 different ways.

Buckle that thing in and enjoy!

Now that I've seen how useful this thing is, I plan on adding a small pen holding cup and a change holder to my box.

Thanks for reading, I hope you find this useful. If you make one please make sure to share the photos hear. Any suggestions to modifications or additions are welcome!