You can still make it constructable but difficult. This is a very very powerful golem/creation that would be guarding a main temple and not something easily done. Difficulty would be high, but still plausable. Less construction, crafting it physically, and more a Ritual/Summoning using materials at hand and the golem rises up out of the slab like the T1000 from Terminator 2.
I'm tempted to say it takes a solid block of black marble/ Obsidian /Adamantite sheet of no lesser than 120,000Gold, a gallon of Wyvern's blood (or poison), and a live Octopus.
The octopus must be killed and it's severed head dipped in the bucket and the contents scattered on the slab why casting the spell. Make the spell a Ritual.
Spell:
CL 14th; Craft Construct, poisonous cloud, x, x, x, caster must be at least 14th level; Price 170,000 gp; Cost 120,000 gp + 7,640 XP
Trying to figure out what other spells you'll need to cast in conjunction to get it to work. This part will take a touch of work.