annw, the packing cubes have a firm bottom and a stiff thin sheet of vinyl to put on top of your stack of clothes. You can also use it as a guide to fold things to size. When you fill the cube, it has velcro flaps to close it across and lengthwise, and it is amazing how many things you can get in them. They hold a lot of clothes, and if you use some plastic cleaner's bags between things they don't get very wrinkled. Of course, you don't want to pull the flaps too tightly or you will get some wrinkles.

I have a large size, two mediums, and two small bags that zip which I use for undies, socks, whatever. One of the small ones holds a two-week supply of underwear. You really can't believe it until you try it. (I couldn't, and my daughter bought me my first medium and small ones to show me.)

@annw

I use it for both actually. Though the saving space aspect of it only really comes into play at the end of my trip when the suitcase is full.

I think the kind of "cubes" mentioned by carolyn are actually the clothing folders. The cubes are just cube shaped bags. Check out Eagle Creek's website for examples, though other brands do exist.

Does anyone know if packing cubes like Eagle Creek makes, frustrate US Customs? Seems like they still might need to open them. I don't need organization, I justs want to get thru Customs. Are plastic bags best?

I use plastic garbage bags, small sizes, for T-shirts, blouses, etc. They weigh almost nothing and are totally disposable.

Ziplock Baggies also made large baggies, larger than the gallon size with the zip lock. I've used up my box and haven't bought replacements. Don't know if they're still available.

Socks, delicates,and smaller stuff like that go into gallon size Ziplock baggies.

The plastic grocery bags are great for shoes.

All the plastic bags I use are as light as possible and totally disposable. I take a bunch of spares along. WEIGHT is a major consideration for me.

Forgot to add: this thread stated in 2007.