How to train an espalier

I want to plant espalier apples, but prefer the idea of training them myself. Can I convert a tree into an espalier or are there special varieties?

It’s great fun to develop your own espaliers and it will not take as much time as you think, but it needs patience and skill.
Start off with whips or maidens – young, single-stemmed trees – which you can buy in any variety. You’ll need compatible pollinators, so choose accordingly.
In the first summer, select your first two side-stems and tie them in a horizontal position, removing a third of their length. The remaining side stems are removed. In following years, train subsequent pairs of sideshoots and prune the current year’s growth each summer.
Get yourself a decent book on pruning so you can follow the guidelines to the letter. Expect to wait three seasons for your first crops, but, after that, you will enjoy heavy yields and will have created your own, beautiful and functional garden features.