I love circles, I think they are visually very pleasing and easy to create a lot of things, you can do very clever things, like what the super talented Pete Hughes does - like dinosaurs, Toucan or uniforms! - or just use them in a much simpler way.
The thing is that many sets of framelits do come with circles as extras, ie, the centre of flowers, and as I keep all sets together sometimes is hard to find the right die for the size I need. this is why I use a custom made Circle Die Template that allows me to see all the sizes I have in one single sheet and see if they will be the right fit.
So I take a piece of card of an unpopular color for me. The reason is that way I kind of warranty that the card will always stand out against any card I will need to cut. (This will make more sense in a photo bellow.)
I place the Framelits and write the set they belong to. I secure them with low tack tape and run it through the Big Shot. Here I am using the Lovely Flowers, Old Labels and Flowers 3 framelits set.
You can keep adding more as and when you get the other circle dies. It is good to do it even though they may be repeated sizes as there may be projects in which you can do with repeated sizes.
Once you have it, it is really useful. See, I wanted to cut that flower, but not sure which circle die would fit best. So I place my circle die template on to the paper, then you can see perfectly which size will fit best and where to find the the die. Because it is die cut out of a "unpopular" color for me, it will stand out against most papers that I have.
I also keep the positives, although I dont use them half as much.
But they are useful when planning matting and layering.
And you can always add more at a later date, or even make a second sheet. Also, it is useful if you are going to a craft shop and you want to make sure you do not repeat sizes. Much easier than carrying all the dies with you.
Of course, you could do this with all of your dies. I personally dont have the time or energy to do that with any but the circles as it is my most used and universal shape. Anyway, I hope this is helpful