Shuttle FV24: the tiniest Pentium III motherboard. Might make an ITX build out of it. : r/vintagecomputing
The Motherboard - Shuttle's FS51 - Shuttle SS51 XPC - A True High Performance Small Form Factor PC
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
Shuttle XPC SN27P2 - Small Form Factor Barebone for AMD Review | Trusted Reviews