I first talked DH into colouring my hair during lockdown and he did such a good job that, to his great dismay, he's now stuck with it. He's generally good with his hands and quick to pick up all sorts of skills from mainly watching Youtube videos (like PCB soldering, fixing mechanical watches, bikes, amps and electric guitars, woodworking, sewing etc.), so I figured he'd probably be able to learn some foiling techniques as well.
I used to spend around €200 and three painfully boring hours at the salon every couple of months for a result I was actually less happy with, so I'd much rather stick with the DIY version now.
If your DH is willing to give it a shot, I can highly recommend the foiling videos by a hairdresser on Youtube named Jamie Dana. She does great step-by-step explanations and also has a video for highlights on a pixie cut. The colour in this one isn't quite my cup of tea, but her technique is sound and fairly easy to follow.
If he doesn't, I'm sure you'll be just fine with all-over colour as well - looks really nice and fresh especially on short hair, IMO.
JMAngel1, thank you, I looked at lots of pictures and wrote down the formulations for the ones I particularly liked (many hairdressers share these on Instagram). You soon end up with a core group of shades (the same letter combinations repeating themselves) that will at least come close to producing the colour you want. This copy-and-paste approach certainly works for different (lighter) shades of blonde if you're working with bleached hair as you will always be starting from roughly the same very light yellow-white (inside of a fresh banana) colour. Darker shades with more variation in the starting point colour will be less straightforward, I think.
To fine-tune shades it does help to understand the Shades EQ colour system. It is a bit confusing at first but actually does make sense. Look at one of their large colour charts and read up on what they call the 'background colours'. I found this explanation quite useful:
https://kristinarussell.com.au/wp-content/uploads/2020/07/Guide-to-Formulating-Glazes-and-Root-Shadows-with-Redken-Shades-EQ-1.pdf