Or, if you belong to a sportsman’s club they probably have a range that members can shoot for free, and guests can shoot for a small fee - if they don’t; they should.
Or, you can get together with a few buddies and build one. This is better as a group activity anyway. More hands helps spread out the labor and costs. It’s also more fun to shoot with a group. One of the groups I shoot with meets once a week and after we shoot the targets, we grill burgers and dogs and shoot the bull.
Obviously, you need a place to shoot. The more ground the better, but you can build a decent course on as little as 1/4 acre. If you don’t own it, recruit someone who does into your group, or consider asking permission of a landowner whose ground you hunt on, particularly if you lease that ground.
For equipment, you need whatever is necessary to clear shooting lanes, and the targets themselves. In most cases that means simple hand tools like saws and loppers, though you may need a chain saw for some of the larger stuff. Most any 3-D targets will work. It helps if they represent the animals you hunt most, but it’s not critical.
Most of the courses I shoot are along woods roads or ATV trails. That makes setting up the course and getting from station to station much easier. If you have a large course, you can even spread the stations out farther and ride from one to the next. With an ATV you can also carry extra gear like tools and perhaps a cooler with snacks and soft drinks, or even portable stands.
Speaking of stands, you should include several in your course. Most 3-D courses are shot from the ground, but most archers hunt from an elevated stand. (Remember the purpose of our 3-D course is to simulate real hunting situations). You can sometimes take advantage of changes in elevation to simulate a stand - shooting downhill. Ladder stands are probably the most practical style for a 3-D course. Whatever you use, always, always wear a safety harness.
Hauling along a portable climber not only gives you a chance to mix things up, it also provides an opportunity to practice using your stand in a non-hunting situation (so you’re not fumbling around in the dark on opening morning of bow season because you never actually used your climbing stand before).
Have fun setting up and shooting your stations. Mix up the distances from station to target, and don’t allow rangefinders. Making shooters estimate range is good practice. Set up in a variety of habitats, topography and cover. Targets may appear closer or father away depending on whether they’re in thick woods or an open field, and compensating for steep angle shots can be tricky. Be creative. Think of the places you hunt, then try to build stations that simulate them. Then practice, practice, practice.