Sorry this is so long, as they say one pic=1,000wds
I too made the 'domed ' shelters out of cattle panels. If you want to make more than one, that could be your best bet. I did mine differently. I used pressure treated 2X4s (on edge,not flat) and made a frame about 4X4 using 3 1/2" decking screws at the corners to fasten. Next I used my drill and a bit(extra long) exactly the size of the cattle panel wire. I drilled straight thru make sure to hold the drill @ 90 degrees, I cut the wires on the ends of the long sides of the panels so I had 6" of wire to stick thru the drilled holes.I stuck the ends thru the frame(you're gonna need help here, and used a 6lb sledge to bend them over so they are held in place. Next I took 1X3s and cut them to 4' lengths, you need 10 of these. Using 2" deck screwsfasten these boards one outside one lined up inside of the dome, using a wire( set the boards so that you can put several screws above and several below a wire) now you have a frame. I used roofing "tin" and screwed it onto the boards starting from the bottom of each side. Different metal come in different widths so get your metal first so you know where to place the boards. Just make sure that they will line up so your topping sheet of metal is held right at the 'peak' and both sides. You can make a floor to slip inside if you want, you can remove it in good/dry weather. This makes the structure easy to move. You can group these end to end if you want, put them against an existing structure thus eliminating one open end., I have mine against a shed. If you want to put in a permanent floor just lay a 2X4 down the middle of the framing (inside) and fasten with the 3 1/2" decking screws from the outside,then lay your boards from side to side and fasten them with nails or screws. I made mine as a temporary measure too, four years later it still looks new. This is a popular place for standoffish goats. I have a couple that would actually rather stand in the rain than go in with "everybody" else. This is why I keep the structures past the need for them, that and I'm just too cheap to throw anything away. I'll probably try a bigger one this fall as I'm making a separate pen for a couple of big wethers and they'll need their own shelter. Maybe 6X6 and use some pallets for side walls to make it taller.
To make a permanent strucure on the cheap, buy 4 8' pressure treated4X4s, a couple of bags of quick set cement. dig holes about 2' deep and 1' wide,about 8' apart set the poles 8' apart in these holes (outside edge). level them and brace them put in stones, then gravel to about 10" then mix and add the concrete. Let this set for at least two days.
Run boards 2x4s around the OUTSIDE of the perimeter about 6" from the ground. Run another course about 16" above that. Now you can figure out your roof, a 2 person job. Use a longer board than 8'. Screw it loosely to one corner post(holding it horizontally. Have the other person holding the other end. Now go to the other end, drop it down about 4" and screw that in loosely. Take a scrap of 2x4 to add the extra for overhang and mark the angle where the upright posts and the roof joist join. Mark the post too as that needs to be trimmed off. Really easy with a hand saw. Now you have a pattern to cut all of you roofing joists. On an 8X8 shelter you'll nee
d 5. Screw or nail the two end joists so that their tops are even with the trimmed post tops Screw an 8' board 3 1/2" down from the post tops across the front and another 3 1/2" across the back. Lay your 3 remaining roofing joists on these, one right in the middle @ 4' the other at app 2'. Screw or nail them in place. You can really use that leftover plywood here. The only thing you'd have to buy here are roofing shingles, roofing nails and deck screws concrete and posts. Roofing shingles in broken lots/slightly damage packages are cheap,cheap,cheap. You can add more framing around 3 sides.I use the 4th side for access(if you want to add a wall on the 4th side, you'll need to add a doorway) and plywood siding if you have them . Putting in a floor on a temp structure is a waste. You will love this as later when you have a barn, a little protective fencing will give you a hay storage area. Just add some 'free' pallets to keep it off the ground(hay).
As far as how big an area you'll need for just shelter, I have and 8X16 three sided shelter and about 15 adults and some kids most of the time. I look in there and they're all snuggled up in half of it. Shelter is one thing, a goat yard is another, mine is about 5000 sq ft. they can go in and out of the shelter and use the facilities in the yard. I let my goats free range(as do you) during two 4 hour periods a day. The 8X16 shelter is more than adequate for my goats, can't say how much others use or how much time the goats spend in there.
Kidding? My goats don't kid in th pen with the shelter. When they get close I move them to the horse barn on the other side. I'm just a sucker for kids so I have a room(walk out) in my basement for them. I've had kids in there since Dec 23rd this year...way too long. I usually let the moms and kids stay in the horse barn (Ruby LOVES kids) for a couple of months, this year tho we have a visiting wether(neighbors moved and left him) that sleeps in there(Ruby took down the doors TWICE) and he slept on and crushed two doe kids, they were in "his" place. Their mom is very petite and naturally polled,she didn't stand a chance of moving Hulk. I think this guy needs a new home.
If you need anymore info, let me know PM and I'll try to give you answers.
Wish I could send pics but we're down to one scanner, older than the hills and slower than molases.