A mini clock case for a popular electronic digital clock kit found on eBay: https://www.ebay.co.uk/itm/Hot-Sale-DIY-Kits-AT89C2051-Digital-Clock-Suite-Practical-Electronic-Components/223249144826?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

It consists of 2 sections: A base which holds the circuit board and a cover which slides onto the base, producing a clean-cut design.

The 4-digit display is visible through the aperture on the cover.

If this is to be sealed in by the end user, a plain piece of acetate or thin rigid transparent material can be used by placing it on the underside of the cover. (This would also keep any dust from getting in to the electronics through the opening.)