From publisher blurb:
Shiny Chrome and Grisly Gears
Mechanical Monsters is a Pathfinder Roleplaying Game monster supplement for your campaign, running the gamut from old-school fantasy to high-tech sci-fi and space-themed games. While fantasy campaigns are the heart and soul of Pathfinder, the game system is abundantly well-suited to games in nearly all genres, and sci-fi influences have been a part of roleplaying games since the birth of the hobby. This incredible collection brings together 140 monsters with detailed ecologies and lore, ranging from gear-grinding clockworks to advanced androids and from alien automata to extraplanar death machines, ranging from a CR of 1/2 to 25.
Within these pages, you'll find over awesome adversaries and gear-driven goliaths from low-level mecha-minions like walking eye robots, rust-risen undead, and ferrofluid oozes to titanic annihilator robots, magnetoclusters, heavy metal elementals, and clockwork leviathans! You'll find creatures from across the spectrum of technological advancement, from primitive ironrot lichen to sorcerous soulbound shells, gear-punk steamwerks golems and sinister cranial dissectibots, to advanced android assassins and bionanite clouds. Mechanical creatures also are not limited to the mortal realms of the Material Plane, as you'll find technocurious fey like the asteray and epokasite fixer, fiends like the composite alorbidaemon and endbringer devil, and living spirit-machines like the tsukumogami and more than half a dozen inevitables.
Mechanical creatures, especially those leaning into clockworks and technomagical hybrids, are easy to incorporate into any fantasy campaign, whether as the products of insular technocratic societies, experimental wizard conclaves, or the leavings of crashed alien craft.