There are many different styles to pinball machines, and you can build yours however you can dream up.
The original design comes from the early 1900's. "Bally Hoo" was a countertop mechanical game with optional legs released in 1931. Bally Hoo was the first coin-operated pinball game and was invented by the founder of the Bally Corporation, Raymond Malon. (thoughtco.com)
All DIY projects start with a budget. For some this is an important step in the process, making sure they get the highest quality product for the amount of money they are willing to spend. For most of us, we don't really have a budget or you would go out a buy one premade, so we are stuck piecing together things to try and make something enjoyable. The budget is still important, otherwise the project just ends up getting shelved and never goes anywhere.
Some people start with a table top. It is very affordable and quick and easy to build. These cabinets are a variation of the mini but do not include legs, and are typically a little smaller, if you have a 19" LCD and 24" LCD you have pretty much all you need to get started.
Other people are ready to dive all in. They find a great deal on a tv or old broken pinball machine and have some good bones to work with. For a several hundred dollars and some wood working skill you can have a machine up and running in a weekend. For those that can't wait there are many websites that are willing to sell you assembled or kit virtual pinball machines to suite any need.
There are several main components to a pinball machine, and a virtual pinball machine is no different. Many people want to try and keep an authentic feeling about their machines to bring back a sense of nostalgia, for others it is all about playing their favorite table, as quick and easy as possible.