The typical acrylic or plexiglass presentation blocks from stationery trade are hardly available in retail but occasionally crop up on eBay. An alternative are Visconti boxes with transparent lid, which do not allow a 360-degree view but show writing instruments very appealingly; enquiries directly to Visconti are mostly not answered; sources are e.g. Mrs. Blankenhorn (fuellhalter.de) and scription.de.