I have a real hate of saggy benches. This spring my husband helped me set some 6x6 pressure treated scrap posts left over from a job into concrete. (I would use full height posts on the next one so I could cover the hives if I wanted to ) But they were free and free is always good.
Here are the posts and the lag screwed 2x8 supporting horizontal boards. No sagging in the middle of the bench is allowed ether.
My framework for the mesh bench top.
Top installed. This is a salvaged product..looks like steel, but in fact it is fiberglass. We cut it on the table saw from a 4x8'sheet. If I did not have this, I would have used welded galvanized 1"x1" cage wire.
Strong and level. Here come 'da bees!
Your bench height is pretty importaint. You can see in the above photo I backfilled with shavings to keep the bench height low enough to be able to work three or four high without too much trouble.
A little later in the summer. This is a south facing bench.
Think it is over built? It holds 20 hives. Now do the math for fall weight for that many double deeps.
Here is a bench I built in 2011 out of steel pipe. The horizontal pipe support was not strong enough to hold the fall weight, however. It sagged and it had to be rebuilt. But you can see the design:
The brackets you see here were salvage from a commercial store we demo'd years ago. I saved them for a long time until I figured out a use for them. Yes, I am a wood and steel pack rat. You'd be amazed at what they throw away on commercial job sites.
I was alone when I made this and had to scratch my head trying to figure out how to put a 'bow' in the cattle panned roof. Rachett straps! Of course! The beekeepers friend. Just use strong zipties to hold the pannel to the pipe.
(The 2x4 gray supports were just to keep the bench from rocking to much.)
Now the concrete cinder blocks were insurance the brackets would hold all that weight
I forgot to tighten all the carrage bolts in one of the brackets..then it slipped during the winter..No harm done, but you can see the roof works pretty good otherwise.
Heres my first bench. I built the framework to hold a steel table top I already had. I built this in the barn, then asked my husbant to help me carry it out to the beeyard. Almost got in trouble for that one. It was quite heavy, even without the table on top.
I really love this bench, I just expanded to much to keep using this design.
Below is a stand I used the rabbit wire on for the top.
My area is very rainy..we need good drainage.
Heres the hive that sits on it. Too fancy for my yard..these I make to sell occasionally.
Hope this gives you some ideas. Better to spend a dollar more and take a little more time making it..or you'll be doing it over again in a few years.