This is very smart...doing this....A few of us on here have got the IKEA Billy bookcases with the doors. For a while I've been searching for a way to lock these doors, primarily as a way to prevent them from being easily opened on the odd occasion (e.g., when we're hosting a party, etc). These Billy doors can't easily accommodate small cupboard locks inserted into the doors because (1) there's little surface area to work with around the door glass, and (2) the surface tends to split with drilling. Anyway, I finally found this hasp on a 3D printing store (Shapeways) and they do the trick really well. The padlock is a MasterLock 653D from Amazon.
https://www.shapeways.com/forum/t/pa...ss-door.26924/
You screw in the hasp base to the top of the bookcase and have a removable L-shape piece that is padlocked onto it and prevents the door from swinging opening. It's not for everyday locking (because it's cumbersome with the padlock on top of the case), nor will it stop an enthusiastic burglar (but what would on a bookcase?). But for those nights you're hosting a party and have a bunch of inebriated guests with BBQ-sauce fingers who want to check out your $50k King collection - they're perfect.