Cotman Studio Palette - Converting into an en plein air palette

I've been trying to get myself organised for en plein air painting before the summer is over and I bought myself first of all a small Cotman sketchers set with 12 half-pans, and I liked it a lot but, y'know, I like to paint with 24 colours, minimum, so I started looking at buying another one, getting some empty half pans and pouring my own professional paints blah blah...then it hit me - I'm never going to paint a finished painting outdoors - only ever studies and sketches - so who needs professional paints, right? I found a Cotman 45-half-pan studio set, which was at a steal of a price - reduced from £65.00 to £27.79 on Amazon UK - too good to miss out on, right? That's like £0.60 per half pan, they're normally £2.50 each in the shops! So, I got it, but, unlike the sketchers set, that is clearly designed for en plein air work, with every pan fitting tightly, this is a studio set in which the pans rattle and I just couldn't see it working in the field without being damaged.

First thing I did was repair the loose paint and remove all the duplicates and colours I hate. I then bought two colours from Winsor and Newton professional range that I can't live without in the field - Green Gold and Opera Rose - and I added a medium to it - compressed oxgall from Schmincke, already in half-pan form. I added a colourchart, backed with funfoam so that it cushioned the paints. I also intended to add some sticks cut from facial sponges to pad between the pans and to be useful in the field too.

My plans to accessorise this are a mini-mister containing 1% solution of Daler & Rowney acrylic flow enhancer, as it is a good way to wet the paints really fast in the field. There will also be some bottles for clean and dirty water, plus a brush. As the set doesn't come with a brush, I chose a 000 Renaissance Squirrel Mop from Pro-Arte, who are rapidly becoming my favourite brush company! It's a beautiful brush with genuine fur, and thus gives a needle-fine point or can be used to wet large areas - perfect in the field where I don't want to carry multiple brushes.