Art pens for 9 year old boy

[Imtoooldforallthis]

Looking for ideas for my grandon who loves colouring. I've got him some good colouring books and would like some pens to go with. He already has the acrylic ones that paint on glass and stone etc. Just wondering if there's anything else that's a bit different to get him

Anyone

My kids like blendable colouring pencils. What about oil pastels for something different?

What sort of colouring pens does he have already?

For 'normal' ones I'd get Berol in an assortment of colours - they last for years as long as you put the tops back on. They probably only have 12 or 24 colours.

Bic do an assortment of 12 colours which are double-ended (fine and brush tips)
Amazon link

If you're thinking of proper art pens Cass Art do a pack of 24 colours of alcohol-based pens for £26.95. Personally I wouldn't spend that much on pens for a 9 year old.
https://www.cassart.co.uk/cass-art-marker-set-of-24---assorted-colours--c/

London Graphic Centre has a pack of Pentel felt tips in 35 colours on offer for £17.45
https://www.londongraphics.co.uk/pentel-arts-studio-set-of-40-fibre-tip-pens

Cowling & Wilcox have the same set on offer for £13.99.
https://www.cowlingandwilcox.com/coloured-pens/30779-studio-set-40pc?gad_source=1&gad_campaignid=19661986269&gbraid=0AAAAAD-2ndnhAGQtwehlWCGP-Vkd8mhvb&gclid=EAIaIQobChMI6cKjm5LJlwMVmJVQBh0CQimrEAQYBSABEgJrJfD_BwE