Most interesting query, and welcome to our forum. May I ask first how you have determined this vambrace is from Sind, and what references have stated the distinction of armour from Sind from other places in India ?
As I admit to knowing little on this aspect of Indian arms, I thought in order to respond I would check a few resources. My first choice was "Oriental Armour" (H.Russell Robinson, 1967) where the author notes the inherent problems in classifying Indian arms and armour (p.93) but notes on p.96, ..some armour is characteristic of one particular state, such as that of Sind, whilst many states used armour of Persian fashion and it is impossible to distinguish one from another".
Despite noting this dilemma, Robinson continues on p.96 , "...Sindian vambraces are of the tubular type, being opened and closed by means of long removable hinge pins. They are not generally cupped to fit up behind the point of the elbow, as in the Indo-Persian dastana, but are straight like sections of guttering".
He continues commenting on the decoration of Sindian armour , ".. the decoration of these armors consists of applied brass enrichments-either simple borders and bosses attached to the plates or complete overlaid panels of embossed pierced and engraved decoration".
There is some brief overview of Sind arms in "Indian and Oriental Arms and Armour" (Lord Egerton of Tatton, 1880 p.136) however nothing definitive toward these pieces of armour. It is much the same with "Arms and Armour: Traditional Weapons of India" E.Jaiwent Paul (2004) .
In "Arms of the Muslim Knight ' (2008, ed. Bashir Mohamed) there are two examples of Deccani vambraces of 17th c. and it is noted similar examples are in Edinburgh and New York. These of course are the same in structural form but obviously decoration is quite different, being embossed with features and heavy application of koftgari etc.
Regarding the technology in manufacturing as well as the material culture of the region, quite honestly it would be nearly impossible to even list the bibliography of references to consult here, especially without more detail on what you are seeking.
Do you collect Indian arms, and if so what is your specific field of interest?
Looking forward to further discussion with you, and hope this has been of some help. As I note, until this evening I had little knowledge on these either so the research was fun
Best regards,
Jim