I feel the same way when people talk about making there own bait but using a ready made basemix, it really isn't the same. I've been making bait on and off for years Simon and I'd like to think I know a thing or 2 about making basemixes up from scratch. There's a lot to go through but if you ever want some info or advice on anything feel free to message me any time.
The best thing you can do is just play about with it though and enjoy it. Some of the first mixes I made I wouldnt dream of making today but they caught fish, worked well and more importantly I really enjoyed it. At the end of the day they eat sweetcorn and the nutrition of sweetcorn is terrible, we can't even digest it.
Anyway, first off I'd start with working things out in a ratio that adds up to 1kg and writing the recipe up in grams and what's really important aswell as the nutrition is making sure theres enough binders in there to allow it to roll and gel together.
200g of semolina and 200g of soya meal work perfect for this and allows a further 600g of ingredients to bep added to make up the nutrition/rest of the boilie.
People slag semolina off but used at a low amount alongside soya meal is very valuable to a bait but adding more will make it more rubbery and not so good of a boilie but it is used in a lot higher amounts in your standard commercial boilies.
Have a play around using ingredients that barbel like such fishmeals, milk proteins, liver, yeasts and spices.
Don't go high on the flavours as there chemicals and to much can put the fish off but remember hydrolastates and liquid foods are different to flavours and can be used at higher levels.
Here's a bait I was making for barbel I did really well on for years but just stopped making it due to time and just finding it easier to buy readymades. Feel free to use it/change a few things.
Garlic essential oil 3 drops
Squid hydro 30ml
Liver hydro 30ml
6 eggs
Semolina 150g
Soya 150g
Salmon meal 200g
Lt94 150g
Pre digested fishmeal 100g
CLO 100g
Krill meal 50g
Kelp 50g
Garlic 25g
Chilli powder 25g
Really simple and worked a treat
I know the semolina and soya levels are lower than I originally recommended but I gave you them recommendations as a starting point for beginning to roll your own. Hope it goes well pal