I 'etched' my own planking with a Stanley knife and steel rule.
For 28mm planks the ruled cuts were 4mm apart. Then I angled the bade and bevelled these cuts to create the 'gaps' between the planks freehand - this was easier than it sounds as the blade naturally follows the initial cut but you do need a very sharp / new blade for this job.
It's much quicker than gluing the planking on.
Agreed, laser etched sheets of planking would be useful. I'm pretty sure Martin at Warbases would do it (bespoke) quite cheaply and would probably add 'eyes' to make the planking even more wood-like. I've had bespoke stuff made by Martin before and was delighted at how cheap it was. My last bespoke order was for four-part 'casualty' clocks graduated to 20 - they had to be designed and made bigger than the smaller 12 point ones in the catalogue and weren't that much more expensive. Send him an enquiry by email.