I got the bins on amazon (here). They are actually sewing bins but I wanted something with inner dividers that could be customizable but also had a larger section for scissors and pencils. I love the bins for the most part - regular sized pencils don't fit in vertically but they can fit diagonally.
Here's what we used inside:
1) Two pairs of scissors. Each kid has a regular pair of safety scissors and a pair of Fiskars pre-school training scissors.
2) A glue stick.
3) Mechanical pencils. I love these Paper Mate pencils because they use 1.3mm lead which makes them harder to break through normal preschool use. They also come in Avenger, Disney Princess and Frozen variety if you are so inclined (we were when we found them on sale!) I also ordered some extra lead and erasers which I keep in my supplies. Each pencil only comes with one lead.
4) Crayola Twistable Mini Crayons - My kindergartener came home during the first weeks of school and showed the twins how to snap crayons in half. We no longer have regular crayons to tempt them.
5) Crayola Write Start Colored Pencils - I've been pretty happy with these colored pencils. They're fatter than usual pencils, though, so go ahead and pick up a shapener for thicker pencils. My only complaint is that I wish they had more colors (specifically a lighter flesh color).
6) Crayola Pip Squeak Skinnies - Most of these have come from Crayola Mini Coloring Pages. My kids refuse to leave the coloring pages in the box because the want to find the perfect page to color. The pages usually get rubberbanded together and the markers put into the art kit. I also ordered a larger pack of the Pip Squeak Skinnies and divided them up among the kids. The kit will hold about 16 markers comfortably.
7) A good eraser - I will always be a math teacher at heart. A good eraser is a must.
8) The writing claw - I bought these a year or so ago when my little lefty with low muscle tone and occupational therapy needs was learning to write. We honestly haven't used them much but still occasionally bread them out for some practice in correcting grip (one twin writes very well, one is still not using a tripod grip and I want him to develop at his own pace). Still, I leave these in their kits for a lack of another storage space.
The kids are surprisingly good at cleaning up their art kits and stacking them up on the bookshelf. Sometimes it takes a bit of prompting but I'm always surprised at how well they do. All in all the kids and I have been very pleased with them. I guess the baby wil need his own kit soon enough!