I have three plastic scrap booking drawer units on wheels. They work well.

guess i'm just cheap, i use the bucket style plastic ice cream buckets and mark on the outside if the thread is black , white or multi colored thread !!!

I use the plastic match box car carriers found in the toy dept at walmart. they are sturdy and cheap but will hold spools on each side. I use mainly maderia thread and they fit the slots. Some other brands might be too wide to
fit. I have each box sorted by color. I do use the larger spools for basic colors that I use for a lot of logos and keep
them in larger plastic boxes .

I use two kinds. These are Floriani cases and the other ones I use are the clear plastic thread cases.

All my thread is stored in plastic boxes, bought some at WM before they quit carrying them and then got two from connecting threads that are double sided. So dusty here with the dogs and our sugar sand this keeps them clean. Have boxes labled by coloror colors and it works out as I can take boxes where I am sewing, not having a sewing room.

I go to the sporting goods department and buy those boxes meant for the plastic fishing worms. They are just the right length for a the new floss and when on a bobbin they are just wide enough to fit inside. I have many, many boxes such as this because years back when Walmart was closing out this type of inventory, I bought two to three of each color for ten cents each. I ended up with lots and lots of thread. Plus, when my sister passed and I got her thread.

Do you mean machine embroidery or hand embroidery. My recent post was about floss for hand embroidery.

Thread Storage
 

I purchased these a couple of years ago at our local flea market and got all for around $ 12.00.They work great for me and as you can see they will also store those other things that you use for machine embroidery like your neb bobbins, stitch eraser, mylar, ect. Please excuse the mess of threads as I have been machine embroidering Christmas presents for almost 2 months now. You can purchase something close to this at JoAnn's and use your 50 % coupons.

I keep mine in a dresser drawer. Here's my thread inspector checking it out.

Bernina was selling boxes. I like OESD thread. Fit their cones and the smaller Robison Anton. I bought those, and keep them in a cabinet with doors out of the light.