Material? Budget? Choices?.....
Do you want a simple budget holster? A Kydex? Leather? Exotic?
With the new Glock 42 .380acp you can have many choices....
Id contact the holster shop or custom maker first. Many are backed up with orders or they may have other delays.
For a simple OWB rig, Id suggest the modular Blackhawk CFC Sportster SERPA. You can convert it to different angles(standard, FBI, cross draw), wear it on different belts, use it with loops or with a added paddle. I just got a new left hand CFC Sportster for my new Shield no thumb safety 9x19mm for about $16.00.
www.blackhawk.com
Other great holster brands include: Milt Sparks, Greg Kramer, Mitch Rosen, Don Hume, Tulster, Liion Defense, G Code, Safariland, Bianchi Intl, High Noon Holsters, Wright Leather Works, Alessi, Sam Andrews, Mernickle, Hodges Custom Kydex, CrossBreed, Hillman Holsters, Ted Blocker.
The Predator leather holster from Wright Leather Works is very good. I like the coffee color,
. Tulster is a cool new Kydex firm with many choices-styles.