Shuttle FV24: the tiniest Pentium III motherboard. Might make an ITX build out of it. : r/vintagecomputing
Used-Shuttle Spacewalker AV14 Pentium III motherboard with 2 ISA slots, 5 PCI, 1 AGP. VIA Apollo Pro 133 chipset. Socket370. ATX Form Factor - Walmart.com
The Motherboard - Shuttle's FS51 - Shuttle SS51 XPC - A True High Performance Small Form Factor PC
Shuttle XPC slim DS10U3 Barebone System - Slim PC - Intel Core i3 8th Gen i3-8145U 2.10 GHz - antonline.com
Shuttle XPC Slim DH410S Mini Barebone PC Intel H410 Support 65W C
Amazon.com: Shuttle XPC Slim DH470C Mini Barebone PC Intel H470 Support 65W Cometlake-s LGA1200 CPU No Ram No HDD/SSD No CPU No OS (Vesa Mount Included) ,Black : Everything Else
Shuttle XPC SN27P2 - Small Form Factor Barebone for AMD Review | Trusted Reviews
iXBT Labs - Shuttle D'VO Series SG33G5M Deluxe Barebone