Perhaps I am a moron, but I searched for hours for a way to avoid using one of those metal folding foundations for my new memory foam mattress... I found things that were similar, that seemed promising but ended up being ads for the folding metal foundations, or were far more work and money than I wanted to commit.
See, I already had a very simple metal frame with headboard and foot-board clamps (it came with the headboard and foot-board, its the kind they often give away with the purchase of a mattress/box-spring). A stand alone metal foundation with 2 sets of brackets for the headboard and foot-board would have cost about $200 more and wasted what I already had. If you don't already have one of these, they are about $5 at the thrift shop.
So, here is what I did.
Step 1: $36 of Stuff to Buy
7 2x4x10s Have the guy at the store cut them in half so you will have 14 60" 2x4s. = $30
1 15' roll of rubbery shelf liner = $5.98 (see my pic of it)
Step 2: Trim the Boards, Place and Duct Tape
Half the boards dropped in my Queen sized frame perfectly, the other half needed about a 1/4" trimmed off. Space evenly, although those at the top and the bottom of mine had to be placed dependent on the welds of the bed frame. The rest fit in with about 2" gap. I used a usb charger with the plug out as my spacer. Then to make sure they wouldn't slide when I dragged the mattress on top, I duct taped the ends to the frame.
Step 3: Bed Risers If You Want a Tall Bed.
I like a tall bed and so I added 5" bed risers. Totally not needed and if they break I will just take them all out.
Step 4: Rubbery Shelf Liner
The old futon I've slept on for the last 5 years had this stapled to the slats, and I thought it seemed more breathable than the cardboard others use under the mattress, so I duct taped some of that on just on the top and bottom slats.
Step 5: Done.
Galumph the mattress up onto the slats, cut open the packaging, side it into place, make the bed, and viola! I added 2 inexpensive thin dust ruffles (one with the sheet over the slats, the other with the center cut out so I could easily pull it out and wash it).
Solid as a tank, nothing shifts or rattles, and cost me $36 (I already had the risers). I purposely bought a 14" mattress for the height, but since they are meant to last longer and be more comfortable, I am happy with that choice. I was going to buy a 12" mattress anyway, but I found a 14" on sale for the same price I was about to pay for the 12", so I don't think of it as having cost me anything more.
This may be so stupidly simple that an Instructables is not necessary for most people. However, I really did spend far more time trying to hunt down someone else's solution to this than it took me to 'build' what I did, so if it helps anyone not waste that time I'll feel better about having wasted my time.