For many years now, I've been intending to make a RIS. Well, back in February I finally did just that. This is the ingredients and method that I used.
I decided to keep it very simple, and started with the following ingredients:
1 x Coopers Stout kit 1.7kg (£10.99)
1 x Coopers Dark LME tin 1.5kg (£4.99 on special when Brewstore closed down)
1 x Table sugar 1.0kg (£0.65)
The date is 20/02/2022. These were placed into a fermenter and thoroughly mixed together with hot water.
I then topped it off to a brew length of 16 litres (all water used was bottled spring water from Aldi @ 17p per 2 litres because my tap water is rubbish.)
Starting gravity was measured at 1084.
With the wort still quite warm, temperature about 24 C, I added the following yeasts:
1 x Coopers kit yeast 7g (from the stout kit)
1 x Safale S-04 11.5g (bought separately for £2.65)
1 x Wherry yeast (this was out of date and added as a nutrient for the other yeasts)
After about 3 weeks in the fermenter (at about 21 C), it had stopped at about 1020 (measured 3 times over about a week) and was ready for the next step.
It was racked into a sanitised fermenter, batch primed with 60g of table sugar (for a lowish carbonation), then bottled on 13/03/2022.
In total it made 28 x 500ml bottles (there was about 300ml extra which was sampled at the time of bottling).
It has just about finished secondary now and should be somewhere around 9.3% by vol (taking secondary fermentation into account).
Total cost was about £20.50 for 14 litres of finished product or approximately £1.46 per litre.
I had a bottle of it last night because I have absolutely no patience

I'm toying with the idea of making another one very shortly using exactly the same ingredients and method as it is so nice and takes so long to mature.
Believe me guys, this is a definite winner if you're a lover of RIS's.
EDIT: Add more information.