wide.. then add 2 more cases and another shelf.. 1 inch boards wont work, they are realty only 3/4" and will sag, unless you have a crate in the middle. 2x's come in 6'/8'/10'/12'.. pick out straight ones.. i usually put them in the sun weighted down, turn over daily for a week or so to dry them straight. depends.. some aren't kiln dried will, they feel damp... and tend to twist if not dried flat.. haven't built anything out of 2x's lately.. check the different grades.. sometimes it pays off to spend a little extra..
at Home Depot on the other end of the isle from the oak boards are some shelving boards that are "YELLOW PINE"...:wow: :woohoo: 1" THICK, VERTICAL GRAIN 4 FEET LONG 11 1/2 INCH WIDE. $9, they have one rounded edge..really nice wood, some has veneerer on one side.
BUT THAT WOULDN'T WORK WITH CRATES, or cinder blocks.. go with the 2x's spray paint the crates, stain the wood and clear urethane.. or paint just them, there are some really nice designer colors now, and matching latex spray can paint
for safety you need to screw the board to the crate from the inside of the top of the crate, down from the bottom of each level and thru the back of the crate into a stud at least the top 2 crates. my nieces 18 month old pulled the bedroom dresser over on top of her, and got a serious concussion.
just use the 1" or 1 1/2" black zip screws,
, usually don't have to drill a pilot hole. except in the crate plastic.
i've been doing this since college 1964, you can do it quick and easy plain or fancy as you want.. there are heavy cardboard tubes for concrete pillar bases, 10" two 2x6's are 11" you can cut then to length cut with a saw, put adhesive shelf paper on them, there is wood grain paper.. solid colors, patterns.
if you use tubes you need to put bass of sand or gravel in them to stabilize them, you definitely need screw them to a stud from the inside.
the tubes are really long .. cut slots/in one side of a 12" dia tube so the shelfs fit tightly, a tube on each end, the tube material is pretty substantial make a pillar on each end... just got the idea.. have a shelf on the bottom cut a piece of 2x glue/nail on each end, screw the tube to that, providing some overhang on each end top and bottom, insert the middle shelves into the slots, glue a wood piece as a stop inside the tube on each side, work up from the bottom.. should look nice with the proper finish..
hope that helps...