Almost 18 year old boy, £15?

[BuilderMammy]

Inspire me. I'm a million miles out of touch with teenagers.

He plays guitar and draws comic strips.

If he likes comics what about a comic book. They have a huge selection in waterstones

other options

Faber Castell do pens for Manga drawing - they sell these in WH Smiths and Hobbycraft and they are £14.99 for 6 pens

Guitar Music?

More generalised gifts could be....

Lush gift box - if he's that type of boy
Recent DVD
ITunes Voucher
Cinema voucher
Costa Coffee Voucher

I was going to suggest a cinema voucher too.

Don't panic he's an adult not an alien! He sound's more alternative than mainstream, so avoid anything too fashion victim. The comic strip sounds like a good theme, buy supplies if you know his style of drawing or a voucher for a local art supplies shop if possible?

Something like <a class="break-all" href="//this?www.google.co.uk/shopping/product/9417739918543956682?q=promarkers+manga&client=safari&rls=en&bav=on.2,or.r_cp.r_qf.&bvm=bv.80642063,d.d2s&biw=1465&bih=915&tch=1&ech=1&psi=Egd2VLy4KMjtaombgXA.1417021203951.3&prds=paur:ClkAsKraX7LuPs9Xa-FCz8mMnruuTsBKvgJzQBBb86D7V630oUmt-OTEUGLd-aylzmWM7AaG8jE85aKNGhM1bcF6T9F4rn6C5ANXFFxojtMNsqpE_jem5OOl_BIZAFPVH72oYL85ldiQk_DcFk7tPK3PrnQ41w&ei=Fwd2VIDUOcjtaombgXA&ved=0CHMQpiswAQ" rel="nofollow" target="_blank">this?www.google.co.uk/shopping/product/9417739918543956682?q=promarkers+manga&client=safari&rls=en&bav=on.2,or.r_cp.r_qf.&bvm=bv.80642063,d.d2s&biw=1465&bih=915&tch=1&ech=1&psi=Egd2VLy4KMjtaombgXA.1417021203951.3&prds=paur:ClkAsKraX7LuPs9Xa-FCz8mMnruuTsBKvgJzQBBb86D7V630oUmt-OTEUGLd-aylzmWM7AaG8jE85aKNGhM1bcF6T9F4rn6C5ANXFFxojtMNsqpE_jem5OOl_BIZAFPVH72oYL85ldiQk_DcFk7tPK3PrnQ41w&ei=Fwd2VIDUOcjtaombgXA&ved=0CHMQpiswAQ

Sorry, that didn't work.

Manga Promarkers

If he plays guitar how about something like this:
www.gettingpersonal.co.uk/gifts/pickmaster-plectrum-punch.htm?utm_source=google&utm_medium=product_feed&utm_campaign=froogle&gclid=CNyQ46uUmcICFcvpwgod0pgAGA