As '鑄造建材' appears as one term, I believe it means 'the making of building materials by casting metals'. Otherwise, there should be 2 separate terms, '鑄造' and '建材'.
The sentence has become very long, and I suggest breaking it into 2. I suggest we change the 'so that' in this new line to 'thus'.
'Therefore, the development of labour-intensive, low-tech or ...
The passage is fine. I suggest minor tweaks as shown below:
I deleted the comma before the first 'and'. The 2 phrases in [ ] can be joined by the 'and' without the deleted comma.
I added a few commas at the ** locations and also 'hence' on the last line.
'Marketing' and 'market' are terms you may want to consider.
My suggestion is
'Generally speaking, ...