Purchased Clothworks hours and hours ago and still no activation email with the licence in it sent through...have sent an email to both clothworks and accounts at @sketchucation.com and no reply. Nothing in spam filters either.
It seems like other people have also had this problem - is there an issue with the automatic licence vendor?

Thanks for the help all - as requested here is a 2015 file version below:
Tunnel Test v15.skp

So Dave I tried that a few times, going like this:

Selecting hidden geometry and copying the image:

Repositioning the image

Sampling and filling around and I end up with this (still not aligned like yours is)

When I check the adjacent segments, why do so many duplicates appear?

You mentioned image sizing - I've tried resizing it (doubling, halving) and it still doesn't seem to matter, I can't duplicate what you did. Also I'm not clear on why the image isn't the correct size...the arc length of the top of the tunnel is 14153mm and 600000mm long, so I thought making a rectangle 14153mm W x 600000mm long and stretching the image to fit that shape would be a logical thing to do?

Do I have to reposition each individual segment?

I'm clearly still missing something and it doesn't seem like anything big but it just eludes me.

Thanks again for the help

I've researched this topic quite a bit and have tried many different ways to do it but am slowly going nuts so I thought I'd reach out for help.

I'm trying to wrap a 2D image onto the inside of a 3D cylinder.
So I've done the usual steps of:

• Creating a rectangle of the same size as the interior of the cylinder
  Importing the image onto the rectangle
  Repositioning it within the rectangle
  Sampling it then applied it to the inside of the cylinder

But it just isn't working. It seems to apply half of the image to one side of the cylinder then duplicates it on the other side (so I'm not getting the full image on it).

I've also tried revealing hidden geometry and applying the image step by step, but it seems like every time I sample and attempt to apply it to the next segment, the positioning goes completely out of whack for each subsequent segment.

I'm tearing my hair out here trying to figure it out. I've attached the file:
Sketchup file
and the 2D image:

I'm trying to get the image to go from the top of the left-side step and wrap around to the top of the right-side step.

Any help is greatly appreciated.