toss a flange fitting down to deck boards (hardware stores = 2",3", 4" toilet flange metal), screw in a pipe to that, run it up to were ever drill a hole all the way through pipe. toss a large bolt with some extra nuts on both sides, toss a couple pieces of plywood on top (one plywood touch bolt, other piece acting like a washer than can freely spin), toss barb wire roll over pipe and onto top plywood washer. if you can find a cheap large plastic tub, or plastic garbage can, for a few bucks, cut yourself a couple circles out of the sides, and place between the 2 sheets of plywood. for a bit more free spin on things.
local hardware store, fence isle (for folks that live in the city style of fencing), you should see some metal fence posts for chain link fence, you might find a flange or like fitting there as well.
drill press + V notch in say a 4x4 lumber + a couple clamps = easiest way i have found in drilling holes in pipe.
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other option...
is just drill a hole in say a 2x4, and align the 2x4's on each side of carray all. and toss a pipe through it. would still suggest plywood washer on each side with a couple plastic diy washers. so when it hangs up on a side, it will still turn. you will most likely need an angle brace for the 2x4's that has the pipe on it. when that barb wire catches, it will snag and rip stuff up.
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5 gallon buckets can be rather nice. to set posts and like in. assuming you have 3 sides, and a 4th side acting like a door (couple hinges, and a *meh* forget name cusp is what i want to say, has a hinge that goes over a spot were you generally place a lock on it.
other option, run 4 posts up in each corner, run some 1x2's or 2x4's around 3 sides, spaced a few inches apart. and for the back side (4th side), make sure you have a bottom lip. and then place a 2x4 up say then 4 feet, maybe 5 feet up pending on length of your posts are. so you can stand the posts up inside, and the posts will basicly lean inside. just reach in from back and grab what you need. vs bending over. ((then menards, lowes, homedeopt, were they have an isle of pipe leaned up on there ends, (pvc, copper, etc...type of pipe)
keep room if you use electric fence / hot fence for animals. 5 gallon buckets are rather nice to toss a few bags of insulators into.
generic fence wire (not barb), just a roll of wire. toss a bolt some place than you can hang a roll of wire off of. so you can reach over and grab what ever length you want, when mending / fixing fences / dealing with corner posts and like.
for your fence staples (wooden posts), to the clips for T posts. find a 1 gallon bucket or large coffee can with a lid. to toss that stuff into. "needs a lid" one little bump and you spend 2 hours picking stuff off the ground in weeds *big frown*
find a spot to shove a couple nail aprons (couple pouches in front that you tie around your waste) to hold fence staples in. seems like i always end up putting a hole in one of them.
toss a bolt on for the water jug, make it on the back, so you do not have to fight everything to get to it!
toss a couple 2" to 4" pvc pipe a couple feet long in a corner or (if on the outside with end caps on them) so you can toss a couple long handle shovels or a rake or like into them.
use another 4" or two pipes. to toss a couple chains in them (toss hooks onto edge of pipe).
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to above build yourself a tool chest! grab the gear you will most likely use, and toss it into middle of the floor. and start adding stuff onto the carray all till you have a spot for all of it!
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jug of water
one of the tools might be a "farm jack" for T posts, to pull the stupid things out, when ya bend one over completely. and and you can not get tractor into spot to remove it.
hand tamper (pipe with a weight on end of it),
some small levels, to string levels.
tape measure
regular claw hammer.
fence stapler hammer/puller
flat bar /prybar
flat head screw driver when nothing else works for a wood staple.
wire cutters
larger wire cutters
tree trimmers (for little trees / branches that always come about either in fence line, or were you want to drive.
wrenches / socket wrenches for fence strecher.
a few pair of extra gloves for when you tear them to shreds with sharp ends of wire to barb wire.
a pencil or 2 perhaps a marker.
weed eater / trimmer, with possibly a brush blade on it. if crud just will not let you to get down to bottom of post to hammer in a staple.
shovel = spade
shovel = flat end shovel
shovel = bull noise wider shovel if ya need to dig some if using a post hole digger.
2 handle post hole digger if ya using post hole 3pt digger, and did not get a good drilling of hole / cleaning of hole.
TIP, get some velcro straps and figure out a way to attach them to a level. makes it a bit easier to strap level to a post. and not needing extra hands or tossing level off to the side.
a fence is a fence, but sure is a lot of stuff needed for them at times....