I'd be interested in the faster method. I'm thinking of building a railway on blocks.
OK, simple version is: ignore all the advice you read about making a smooth, level concrete bed. Dig or identify a rough plan for your desired route to a rough level (or to any gradients you want), compact it if not already well solid, lay concrete in a dryish mix to about a four inch depth (so it just about supports itself - the sides need to remain nearly solid - you will need to experiment a little bit to get that right. Do NOT use any detergent or mortar treatment, that we would normally use to keep mortar or concrete workable for longer) and plonk your blocks on to the mix - the key part is getting the blocks level when setting on to the concrete. With this method, no need to use formers, and no need to get a perfect level for the base layer of concrete, which saves days and days of effort. It has all set just as I wanted.
I also put some metal strengthening into the concrete - old scaffold poles or other similar lengths of metal trim or grids - but that is because the earth here moves a lot. You may not need to worry about that. In England, I used lightweight blocks for the most part, and had no problems (paint them first to make them more resistant to frost damage) but I dare not use them here, as the strength of the heavyweight blocks is part of the resistance to earth shrinkage and expansion.
Then if you need further height, just lay further blocks on top of the base layer, using normal mortar, after the concrete has gone off in a few days.
Mind you, I have used a concrete bed alone (with no blocks) as the base in a certain part of the garden, where old tree roots and some very large rocks would have made proper prep a nightmare. Time will tell if I have made the right decision!!
EDIT - PS - I forgot to say that a metre long (or longer) good quality spirit level is absolutely essential to get this right! You need to constantly check your levels across three blocks, not just the adjacent ones. That will ensure you are not accidently over-compensating for one rogue block.....
Edited by Mike Storey, 14 June 2018 - 19:47 .