I keep forgetting to say that I've done hand/foot prints for both Verity and Wade when they were little and I used a large ink stamp-pad same as banks and libraries used to use when they had to stamp passbooks and books. The ink takes a few showers to wash off but the quality of the prints is amazing: every little line and crease... I'll have to scan them at some stage to show you all. Acrylic paint might turn out as just a blob. Also try to use acid free or good quality thick paper or card so that it will last.