Imitation is the sincerest form of flattery, or so they say.
I recently returned from a multi-week bouldering trip. Our local member's party was coming up and I planned on setting for it. I had just experienced a few new outdoor areas for the first time - including the stunning granite paradise of central Washington. I was more than ready to put brush to canvas, as it were.
I was especially eager to try to recreate one of my favorite problems from the trip. I've done this a bunch of times before, but this was one of my more successful attempts, so I thought I'd try to break down my thought process. Most of this applies to creating a route from scratch in your head, but specifically this post is for trying to "carbon-copy" a route.
First, think about it beforehand. Does the route's movement lend itself to indoor setting? The more complex the sequence, the harder it will be to find the right wall terrain and holds to recreate the movement. In this case, the moves were relatively basic, but still felt fresh and classic. Even better, there were only three of them covering the distance from the start jug to the victory jug. You only used each hold one way, which helps - outdoors, combinations of holds, different hand positions and different thumb catches are plentiful. Fewer holds and moves make the route simpler - the simpler the route, the easier it is to emulate.
Analyze body positions and movement before hold type or hold placement. In this case, the movements were all pretty basic, so there wasn't much to worry about. In complex cases, try to analyze where the climber's center of gravity goes and where their points of contact are rather than the actual holds they hang on to. Real rock is complex and intricate. Working with plastic holds means we're limited to a convex environment, working above the surface. Real rock frequently has concave holds. Many gym feet have an edge that doesn't sit quite flush with the wall; real rock doesn't have this limitation. Because of these (and myriad other) issues, you'll need to worry more about the position the climb puts the climber in than the way their fingers feel on the crimp. Having pictures or a video of the route itself will help "troubleshoot" the trainer to see why moves aren't quite what you expected - feet too close, holds too good, etc.
Choosing the right terrain can be frustrating. In my case, the problem took place on a 5-10 degree overhanging blunt arete. Nothing like that really existed in our gym, but we had two sharper aretes that were lightly overhanging. The first move was a heel rockover, so I wanted the route to start at waist height or higher to prevent dabs with the hanging foot as you pull on. One of the aretes didn't have bolts in the right spot for the starting foot, so I got creative. I used the other arete and set the whole route mirrored - so you do the first move with your right instead of left hand, and the second move with your left instead of right hand, etc.
Choosing the right holds requires quite a bit of forethought. I had some time to think about it on the drive home, so I had a good idea of what I wanted to use by the time I got there. The holds on the real route are concave slopers, so I had to use some pretty low profile holds to make it work. However, if you have a good grasp of the body positioning for the route, it's easy to fine tune holds - just get on the route and see if it feels the way the real one did. If you have a wider variety of body position options then the hold's probably too good. If you can't do the move the way you did it on the route, the hold might be too poor.
Overall, be ready to make some concessions. Yep, my route was mirrored. You might not be able to make the crimps quite as crimpy or the slopers quite as slopey. It's a fact of life. As long as you capture the essence of the route, that's fine. Usually my trainers end up being easier V-grade-wise than their inspiration. And, of course, in many cases you can only set a sequence you like before terrain forces you to take the route somewhere else. And that's fine too.
Persistence will go a long ways in this endeavor. As every routesetter knows, it can be frustrating to try to create a move you have in your head. Sometimes, trying to create one that already exists in stone can be a nice mental exercise.