I usually fit my flatbed trailer with a box for glass recycling. Usually I just strap it on with rope or velcro straps. the box is good for shopping, hauling rubble/gravel/loose waste, transporting garden tools. It is also handy for carrying bikes, layed on top.
I use the plain flatbed if items wont fit in/on the box, eg 25kg cement bags, lumber, compost in bags .
How do you use yours?

I have a home made flatbed that started life as a kid's trailer. It was well used when it came to me, and I retired it from kid hauling when I judged the condition of the fabric to be too deteriorated for my precious cargo.

I made the flatbed to fit up to 4 totes, in two stacks, and in such configuration is served me well. One noteable use was hauling a picnic and toys and lawn chairs down to the fireworks display for Canada day - good load when all was said and done, especially adding on the toddler in his seat on the back of the bike.

Recently the trailer has gone back into kid service though. I have kept the flatbed configuration and bolted two chairs to the deck in opposite corners - one facing front and the other back. Kids love it.

But I miss my cargo capacity ... probably thinking to rebuild the trailer with a removable locking box box designed for kids to sit astride, with a padded top.

Working ....

I've got a big Rubbermaid Chest with a Lid, or a long 'Put your Backcountry pack in it' duffle bag I can load up ,
moved my clothes on their Hangers when I changed addresses..

and of course a hank of Parachute-cord, to tie down virtually anything.. wrapped in a tarp if needed..

1 ton rubble bags are good for this.

I am a bit still wishing that I had a flatbed. But, I have a 14gal tote that holds as much, or more, weight than I wish to carry. I could get more lightweight (featherweight) stuff on a flatbed but I'd worry about side winds.

Still new with a trailer. A cheap one at that.

this is my flatbed

You can make this one.

I'm hoping to start work on my own flatbed sometime during 2015. Trying to design in my head at the moment. I want 26" wheels to have one tire/tube standard for the whole house. Low on my priorities at the moment since the Winchester still works.