Why make art no-one can see?

Bob and Roberta Smith

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Media captionBob and Roberta Smith, aka Patrick Brill

Bob and Roberta Smith - one man but with two names - is a painter and sculptor from London.

He has a number of works in the Tate collection and was one of the British artists chosen to produce a poster image for the 2012 London Olympics (image 12 in this picture gallery ).

Smith, real name Patrick Brill, is best-known for making funny hand-painted signs on wooden panels.

His DIY approach borrows from the languages of folk, punk and alternative protest movements, using subversive humour to challenge established values.

One of his current projects is a large sculpture of the singer Amy Winehouse, who died last July aged 27. Handmade from wood, on it he is painting words explaining his own thoughts on her life and talent.

Paa Joe

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Media captionJoseph Ashong is one of Ghana's foremost figurative coffin-makers

Joseph Ashong, known as Paa Joe, is the foremost coffin sculptor of his generation, continuing the tradition of figurative coffin-making in his native Ghana. His work is held in museum collections around the world including the British Museum in London.

Ashong's sculpted coffins blur the line between art and craft. Each work is carefully constructed to reflect the ambition or the trade of the person for whom it was made. The aim is for the coffin to be an affirmation of life.

The coffins are a contemporary embodiment of traditional tribal burial rituals and art practice. They link back to pre-colonial West African sculpture but also recall the pomp and extravagance of ancient Egyptian royal tombs.