Extra Large Cat Box With Custom Flap

I have seen other cat boxes, but none have a custom flap and is this large. We have six cats and need a large litter box. Other than the purchase of the bins, I had some spare hardware laying about that I used for this project. Screw size is not critical, but needs to be able to fit through the holes on the hinge. I drilled custom holes to hold everything tight.

The tall bin will be used to as the cat box and the short bin will be clamped down as the lid. This picture is looking through the finished cat box with the door on the opposite side.

I selected the Ikea bins since they are flat on the inside. This allows one to easily scoop the cat litter. Most bins have divots of some type where cat urine and solids can collect.

Ikea large bin for main box -

https://www.ikea.com/us/en/p/samla-box-clear-9010...

Ikea large short bit for lid -

https://www.ikea.com/us/en/p/samla-box-with-lid-cl...

Section of piano hinge -

https://www.homedepot.com/p/Everbilt-1-1-2-in-x-12...

Aluminum Angle -

https://www.homedepot.com/p/Everbilt-1-in-x-96-in-...

Screws, washers, lock washers, nuts - size was what I had laying around

Clamps to hold lid -

https://www.harborfreight.com/spring-clamp-set-14...

Plastic cutting tool - I used the Dremel Multi-Max

https://www.homedepot.com/p/Dremel-Multi-Max-MM35...

Drill, drill bits

Screw driver and wrench

Start with using the large tall bin. I centered my door on the long side and just under the lip.

Cut the hinge and angle to the desired length. Lay down on the side of the bin and mark where holes are to be drilled. This picture shows the hinge and the holes through the bin and the angle drilled.

This image shows where exactly the hinge will be located, and the second set of hinge holes have been drilled. I have marked the door size. Note where the line is located relative to the hinge point. There will be some plastic trimming later.

This door marking is 9 inches wide and 7.5 inches high. The bottom of the door is about 5 inches from the bottom of the bin so that 2 to 3 inches of cat litter can be accomodated.

I have started to cut the door out using the Dremel Multi-Max. I did not complete the cuts in the corners. Note that I marked which side is out on the door so that it will fit properly when everything is assembled.

To finish cutting the door out without things dropping on me, I used some tape to hold the door in place. Finish cutting out the corners.

Here is my hardware set I used. When assembling, do not put the nut or screw directly on the plastic as it will stress it and lead to cracking in the future. I use flat washers against the plastic. I also use lock washers to keep the screws / nuts from loosening up over time.

After trimming the excess left-over from cutting from the door and bin, I place the door back in place and taped it centered. Now add the hardware. Do not tighten all the hardware until everything is in place and slightly snug. Then tighten all the nuts/screws. This way the door remains centered.

Trim additional plastic along top of the door or on the bin around the hinge to ensure proper movement inward and outward. Here I had to cut another 1/8 to 3/8 inch from both sides. I used a small dremmel tool with a cutting wheel to perform this.

Here are the final close-up views of the hinge area. This door was such as snug fit that when I knocked it in either direction, it tended to stop in place without continual swinging.

Now add the cat litter. Then add the top and clamp in place. This is installed on top of some cheap outdoor turf to help gather any excess cat litter as the cats walk out of the box.