A simple 3d printed catenary set that is both affordable and easy to install.
Admittedly, it is not prototypical per se - but it is enough to give the impression of overhead electrification, especially for earlier era layouts.
Each set includes a post, a base to locate the post, a wheel to suggest tensioning wires, and the catenary "wire" itself. Although the "wire" is just 3d printed like the rest of the model, with a couple of coats of metallic paint, the effect is quite convincing as you can see from the final pictures.
You will need one more each of the post, base and wheel than catenary wires, but just order the number of wires required and I will include the extras (for example, if you order 10 sets I will send 10 wires and 11 posts, bases and wheels)
The posts stand 10 cm tall, but can be easily cut down if you prefer them closer to the track
The catenary wires have a span of 22 cm