How Would I Create This Kind Of Model?

I want to make this sort of ironwork for my unity game, using blender:

I don't want it to be too expensive in-game, but I'm trying to make it look realistic so I don't want it to be flat either. How would I achieve a 3d look without lowering my fps? Tips for model making?
I already tried decimating a higher-poly model and giving it a normal map, but it looks angular and strange:

Please help!

 

sculpt a highpoly version and retopo a lowpoly version on top of it, bake normal maps
or you could make a plane with an alphamap + normalmap, which would propably work for most cases
as is see it these pattern have a cylinder left and right, in which case you could model the cyclinder and use the plane in the middle and it wouldn't even be that obvious

 

I have another alternative you can consider: Render this out as a 4K texture from Substance Designer, with the following maps:

• Diffuse (base color)
• Normal
• Detail normal (for the iron grain)
• Metallic
• Roughness
• Opacity (white for the iron work areas, black for the gaps between)
• Parallax

To make use of the opacity map, you would use a shader in Cutout render mode. That can be done with the standard Unity shader.

To use the Parallax map, you need a special shader. I have used the UBER shader from Tomas Stobierski, available on the Asset Store, to render things like this. His shaders are really high quality, and the entire object you showed would be just two polygons if rendered that way.

I used this technique in an archiviz project to render ventilation panels that attach to the walls about half a meter off the floor. Even if the viewer is within a meter of the object, the parallax map allows the object's surfaces to occlude convincingly.

There are two downsides to what I propose:

1. Although it is pretty convincing if done right, it will not hold up against *really* close examination in game, especially if the player is able to look at the object from an extreme side angle. From behind, you'd need a complete mirror image version.
2. Until you've done it a time or two, setting up that parallax map is not (at least, to me) intuitive. Tomas provides really good examples with his UBER shader asset, but even so it's challenging to understand how that specific map works.

If you can live with those drawbacks, though, you get very good results and reduce from "hundreds, or thousands" of polys to "two" polys. In a lot of situations, that's a good trade, but it depends on your situation. In my case, the ventilation panels worked nicely because it's impossible for the viewer to get inside a wall and look at the back of them. I used the same technique with fluorescent light panels at ceiling level, again because they're 3 meters up and can't be closely inspected by the viewer.

(Disclaimer: I don't have any financial or personal relationship with Tomas Stobierski or his company. I just use and really like his shaders. There are probably others in the Asset Store that can do similar things, but this is the package I know from personal experience can do it.)