There were hundreds of Welsh weaving mills in Wales, and thousands of looms in weaver’s homes, which produced good quality cloth, mostly from wool which was gathered, spun, and dyed locally.
Jenkins, J Geraint, The Welsh Woollen Industry (1969)
Skeel, C.A.J., The Welsh Woollen Industry in the 18th and 19th centuries. Archaeologia Cambrensis, (1924), pp. 1-38
There is a long and detailed chapter on woolen manufacture in Merionethshire in Aikin, Arthur, (1773-1854) Journal of a Tour through North Wales and a part of Shropshire with observations of Mineralogy and other branches of natural History  (London, 1797), pp. 69-84