I have several obstacles at my place including: labyrinth, star, tires, "scarey" thing for squeeze game, bridge, tarps, platform, "L", pick-up sticks (logs), barrels, straw bales, cones, etc.
The star is a tire with 4-5 8' peeler logs leaning one end on the tire and one end on the ground. You can lead your horse around the star which helps with the neck stretch by him looking down, practice on where to place his feet, help for lifting the lazy hind feet. It is very beneficial for bending the body. Walk a couple of times around, both ways.
There's so much to do with old tires! As Yana shows with Shaleema, a single tire can be used to ask the horse to place either front feet or back feet in. Thereafter, you can practice turns on the fore or hindquarters.
The tires can also be set in rows of two (maybe 8 tires) and have the horse walk straight thru placing individual feet in the center of the tires. Good also for the neck stretch and thinking about where to place feet and getting the lazy hind working.
A jumble of tires, some placed one end leaning on top of another, is another creative way to use tires. The horse gets to practice some depth and height perception.
Peeler logs can be used the same way. This is "pick-up" sticks. Just 6-8 logs tossed together for the horse to walk thru.
Then the logs can be spaced apart, parallel, in same distance apart or varying distance apart, again helping the horse to learn to place feet, stretch the neck and head down, and work the hind.
Tarps can also be placed under two poles and ask the horse to walk onto the tarp. If there is hesitancy, be sure to click for looking at the tarp, acknowledging the tarp, shifting weight to the tarp, any forward movement towards it, etc. It also may be helpful to have the logs placed in a V shape, sort of "tunneling" the horse toward the tarp.
The bridge is useful for trailering preparation. Ask the horse to step up first with only one foot. Click and reward for any slight movement toward the goal. Good time to reinforce your backup cue by asking him to back away and start again. The horse may paw at the bridge, but he's just checking stability--I usually click for this.
Once the bridge is accomplished, the platform is generally a piece of cake.
The "scarey object" is something you can use to practice the squeeze game. I have an old roll of fencing covered by an old tarp. Pretty ugly. I place it about 3 feet from the fence; and the opposite side of the fence has a huge trash can. Practicing sending your horse between things like this will make him less claustrophobic for trailer loading. At this point, I also have a tarp that can be attached to the top of the fence, held by me or another person (depending on how good the horse is at the send), and then the horse is going between and under "scarey" stuff. Good pre-trailering practice.
The "L" is 4 logs shaped into an "L"--two on one side at right angles, and two about 4 feet away at right angles, so that you have a "corridor" to walk thru. Great for practicing bends, and don't forget backing thru the "L"--horse really has to have his brain engaged!
Straw bales to walk over, jump over, or side pass over, not to mention asking him to bring his front feet up on them.
Barrels--practice leading your horse in and out of a line of barrels or cones (weaving). Then progress to "sending" or "driving" him in and out of the barrels, ultimately to have him to it at liberty. Click any positive progression.
Now the labyrinth--my favorite! It seems like it's so easy to do--lead your horse thru the labyrinth--big deal. Well, it helps the horse judge where to place his feet, gets some neck stretch, some body bend, etc. But my ultimate goal with the labyrinth is to have the horse follow me thru at liberty! And adding to that, I ask the horse to change sides as we turn the corner. If we start the labyrinth with a right turn, I want to be on the inside of the turn, and the horse should be on my left. As we approach the next turn, left, I again want to be on the inside of the turn, so the horse has to move to my right side. If you can get to this point, you have a really cool horse! Not to mention extremely smart!