RTR wagons are increasingly being offered. Skytrex, Dapol and Lionheart offer a wide range at very reasonable prices. Again, look
for second hand wagons already built.
There is an excellent range of plastic kit wagons from manufacturers such as Slaters and Parkside by Peco. They are easy to assemble and
paint, and look very good when complete. They come with all required parts so there is no need to trawl the shops and trade for extras
like wheels, couplings and buffers
Coaches
Ready made coaches are somewhat less common, but again Skytrex can offer some simple BR style coaches at low prices. Chinese built
and painted coaches are also available, and offer fair value when the time to build your own is taken into account. Some suppliers
of coach kits such as Sidelines also offer their coaches ready built and painted.
There are some plastic coach kits available but the bogie ones are more complex to
assemble and more expensive than the wagons. There was quite a range of cast resin kits from JLTRT.
The level of detail is exceptional, and they fit together well.
There is a wider range of etched brass kits, but some skill is needed to build and complete these kits. (see the comments above for locos).
Electrical
Most 0 gauge locos are powered by electric motors driving the wheels and work with the normal 12 volt DC system,
although sometimes higher voltages are used. If you are buying second hand stock check that the voltage is as expected.
Usually because 0 gauge engines and stock are heavier than OO gauge stock the current drawn is higher and therefore
heavier duty controllers need to be used. If you are starting in O gauge then it is recommended that the modern DCC
system is considered (DCC is Digital Command Control). There is a slightly higher initial cost involved, but the
benefit is much simpler layout wiring, control of all engines simultaneously, control of points from the same
hand held controller, and the ability to fit sound to the stock. Having sound transforms the enjoyment of the layout enormously.
Summary
The best advice is to start small. Decide first on what you would like to model, be it pre-grouping, post grouping, nationalised or
whatever. Choose simple prototypes first. It may be wonderful to have a express 4-6-2 pulling 10 pullman coaches, but consider whether
you would ever complete the stock and do you have the skills.
Build the skills slowly; visit the Gauge O Guild shows and talk to the demonstrators.
They have great advice to impart. If you can, join a club and ask advice. When you think you want to buy a kit, open
the box before you buy and inspect all the parts. If it all looks too much work then it probably is, and maybe you'll never finish it.
Say your apologies and tell the seller that you'll buy one when your skills have improved !
But most of all, persevere. There is nothing more satisfying than finishing a model to the best of your ability, placing it on a layout
and admiring it. For the next model, consider how you would make it better.
Be inspired by what others do and use their standards as something to aim for. Buy the best tools.
They are worth their weight in gold. Enjoy what you do; it's a hobby after all.