David Harber has a range of sundials and garden water features which can be personalised. This would be a fitting tribute to your father and ultimately become a family heirloom. Another idea would be to have a garden bench inscribed. You might try Gaze Burvill, designers and builders of outdoor furniture in steam bent oak for a wonderful garden bench . Also try The Letter Exchange for ideas. This society can recommend professional letterers in all disciplines (stone carvers, sign writer, calligraphers) all over the country, and they might have some interesting ideas.