I’m putting together a large “pre-cut”/ pre-drilled gazebo.
The manufacturer enclosed an Allen Wrench, but I’ll be here all day and night using it to put together all these parts. What tool should I be using?
If you have a drill or power screwdriver, you can get a hex wrench bit the same size as the Allen wrench. One trip to the hardware store and it will save you a bunch of time and headache.
Cordless driver?
ETA I see this has already been mentioned. Most of them have adjustable torque which you should set appropriately.
You can get hex head socket kits for your socket wrench. I have this one. I’m a big fan. Infinitely better than a crappy Allen key.
If you have an impact driver, you can also get hex bits for that.
If, like me, you’re too lazy to go to Lowe’s, take your hacksaw and cut off the business end of the AW and insert the cut end in the previously mentioned drill/power/cordless screwdriver.
Nah, prolly a bad idea.
If it’s a decent quality all key it’s probably hardened and tough to saw.
GaryM
^ Thanks, GaryM.
It won’t be too hard, maybe case hardened but not more than that. Notice how the allen keys wear out before the bolts get stripped? I have used a hacksaw to do exactly in the past…
But likely possible to break due to a certain degree of brittleness – put about half of it in a vise and whack the protruding part with a hammer.
They’re not that hard. Especially the ones that come enclosed. Do you really think they’d spend money hardening an allen key intended to be used once?
I did snap one once and while grinding the tip back to a usable shape I noticed the sparks from the grinder gave the impression it was somewhat hardened steel. But it’s been quite a while so I might be mis remembering.
Interesting. Well, put it this way - if you can’t hacksaw through it, you can probably snap it. 
I too recommend the use of a hex bit socket, like the one friedo mentioned upthread. You can buy one individually in a hardware store for whatever size you need if you don’t want to spring for a whole set. Get one with a 3/8 drive for use with a ratchet ( and extension, if needed ).
It’ll be much easier than the unwieldy “L” shaped allen key, especially in tight areas where you can’t rotate it fully around. I think it’s better than using a drill/screw gun because the higher speed of the power drill can cause friction heat binding, and usually the hardware provided is cheap stuff that’ll snap from too much torque and heat.
Or that the bolts are hardened? I would use slow speed/low torque on my drill to avoid damaged bits or bolts.
And wear eye protection!
A t-handle allen wrench is much faster than the tiny right angle wrench they include with flat pack furniture.
Buying a set of T-handle is a good investment. I have SAE and metric sets.
Now if you worry that the power drill does damage, you can get electric screw drivers,
or even a hand operating screw driver that does 4 X speed at 1/4 the torque, so the torque is way down … (naturally you get normal hand torque at 1X with it)
They just use the hex sockets.
I, too, endorse this. A hex set should be in the $20 range, and will pay for itself in the Advil bill alone. Just make sure you put your drill on its lowest torque setting and set the clutch in the 1 or 2 setting.
Hacksaw? Pfft! Too much work. Snip it with some bolt cutters. One and Done!
Now I gotta go to Lowe’s and get bolt cutters.