I need an adjustable strap

I'd look at some of the small ratching tie down straps they have for holding cargo, etc. They have them at HD, Lowes, HF, etc.

Like this:

You may be able to find smaller ones too. If the link doesn't work, just search fo r" tie down" at Lowes.com

Home Depot has 4 packs of adjustable cargo straps ($10-15 or so) that use cam type binders and have about a 6' extended length. These are what you need, the ratchet type ones are too long and too fussy to be useable for that application.

I agree on the cam buckle style of strap - much easier and faster to use. If you happen to have a Harbor Freight in your town:

Seems to me you need bungie cords. They shouldnt' be found under adjustable, but if anything, under elastic. Maybe it's spelled bungee. Or elastic.

Based on the last picture, I assume you want to strap the things to the handtruck, not to keep their lids on.

From the picture, I can't tell the difference between buckle straps and crank straps, but the second or both might be able to crush the vinyl boxes you have. Especially if you make them tight enough that the hooks stay where you put them. Since the straps themselves are at most barely elastic, the tightness will have to come from compressing the tupperware. which I don't think you want. .

FFS! Use a bit of rope. Don't you know how to tie a knot?

these:

these:

That's what I'd do, if a person doesn't know this knot, they ought to, you'll use it the rest of your life. You can cinch things down nice and tight.

org.mozilla:en-US:official&channel=np&source=lnms&tbm=isch&sa=X&ei=LAqpUfHKOI

rk8gTQzoEQ&ved=0CAoQ_AUoAQ&biw=1579&bih=743

or

You're devious. Six so far.

I'm jumping in late here, but when I move my daughters in and out of their college dorms, I use the same style bins as you showed, but I use a mover's dolly instead of a hand truck. I stack the bins 3 or 4 high and then strap them down with ratchet straps.

I screwed 2 more 1 x 4's across the open space because some bins barely reach the carpeted cross pieces.

By using the dolly instead of the hand truck it's easy to push the stack of bins up hills, into (crowded) elevators, down the narrow dorm hallways, etc.

I love watching the other families watch me as I move a bunch of bins, mini-fridges and other stuff on the dollies while they are struggling with plastic bags, suitcases and boxes that are falling apart. I just zip right by with my dolly as they are dropping stuff and fighting to get through doors.

these:

these:

I worked as an electrician for 20 years. Most of the stuff we did was pretty light work, but installing the switch gear electrical supply was very heavy stuff.

There were two different methods. Get 20 or so men to grab it and growl or bring in the right equipment and do it with 4.

I hear ya!

A wise man once told me: "If you're working too hard, you're probably using the wrong tool."