I can recommend the garden shredder as a scratter. I modified the top to get whole apples in. I catch the scrat in large plastic tubs, the kind that plasterers use for mixing in.
I remove the blade and exposed moving parts after use, and washed them down and dry them. They are then stored in sunflower oil. This is washed off prior to reassembly. I then spray them with Starsan prior to use.
I made a pressing board from inch marine ply and put a rim around it, screwed down from underneath and sealed with food grade silicon sealant.
The pressing board has a modified sink waste, with plug, to allow the juice to drain into the fermenting vessel. It also has a raised centre section.
I cut the top off a bucket about 3 inch deep to act as a cheese former. The cheeses are made by lining them with muslin, adding the scrat and then wrapping the muslin over to seal them. They are made on individual boards of inch marine ply and stacked. I can press 5 of these at a time.
The press Is a cross beam type that I made from an oversized (thicker) version of a pallet. I use a 6 ton bottle jack as the pressing mechanism. It is helpful to put a sacrificial piece of wood between the press top beam and the piston of the bottle jack, to prevent damage to the beam.
For 2kg of apples I get around 1 litre of juice, so based on weight the system is around 50% efficient.
The real faff is making the cheeses,
I used to try and get every last drop out of the scrat, but quickly realised that most of the juice comes out on first pressing.
If there’s one scratting and one pressing, then we can get around 40 litres of juice per hour.
Cost was less than £100.
You’ll never make a living off it, but if you like cider, then it’s far nicer than turbo cider.
I had a few bad batches allowing the juice to ferment off natural yeast, so nowadays I use Campden Tablets and wait 24 hours before adding packet yeast. I normally buy a 100g bag of cider yeast and added a good heaped teaspoon to each fermenting vessel.
I joined freecycle and put out adverts on the surrounding area(s) asking for apples and pears for cider and Perry, in return for some of the product back.
I have a really good network of donators in the local area, and most of them contact me each year to offer excess fruit, once they had tried their own cider. Some even saved me the bottles.
Good luck with your project.