I've just acquired a 12" Dob from the local Astro group.  I'll post images later as I can't resize them properly on my phone. The scope is of the Heath Robinson ilk with the main tube comprising 14" diameter plastic pipe. The primary mirror cell looks like it's made of wood and the Base is a fairly conventional DIY dob base with plumbing tube for that Alt bearings. The secondary mirror is chipped around the circumference but the coating looks OK.  The primary looks mostly OK but has a