Although we have some evidence of armour being imported into the Lahore Empire of Maharaja Ranjit Singh, such as the 500 cuirasses and 2000 stands of arms from France that General Allard brought to Punjab in 1836 , armour was also manufactured in Punjab by native artisans.
There was a thriving industry with highly skilled craftsmen that produced armour including helmets in Punjab, meaning that armour did not necessarily have to be imported from other regions of South Asia or Europe.
The arms, which are principally made at Lahore, consist of swords, spears, matchlocks, muskets, pistols, and armour, the latter being composed of helmets or skull-caps, coats of mail, breatplates, gauntlets, and shields. (Steinbach, 1845) 
While visiting the Sikh Kingdom of Patiala during a trip to meet Maharaja Ranjit Singh in 1837 Henry Fane noted that armour was manufactured in Patiala:
After the durbar, a quantity of things was produced: among them a beautiful suit of armour, as a specimen of his country manufacture, and as a present to the chief. (Fane, 1842) 
Even after the end of the Sikh Kingdom of Maharaja Ranjit Singh, there were still craftsmen present who had once worked on Sikh armour at Lahore and Amritsar. In describing a group of Sikh arms and armour including helmets that were displayed at The Punjab Exhibition of Arts and Industry of 1864, we find references to the old craftsmen of the days of the Sikh Empire:
Koft-gari arms, contributed by Sirdar Bhagwan Singh of Amritsar, consisting of the long native gun, daggers, swords, helmet and armour. There are still some workmen, relics of the Sikh days, both at Lahore and Amritsar, who can, to order work up swords etc., in gold inlaying, and do it beautifully, if allowed expenses for a liberal supply of gold wire. Imam Baksh, Mehtab Singh, Amanulla, and a few others are the Lahore workmen. (Baden Powell, 1872) 
1. Jean-Marie Lafont , Fauj-i-Khas, Maharaja Ranjit Singh and his French Officers (Amritsar: Guru Nanak Dev University, 2002), 101
2. Lieut.-Colonel Steinbach, The Punjaub; being a Brief Account of the Country of the Sikhs (London: 1845), 59
3. Henry Edward Fane, Five Years in India, Volume I (London: 1842), 60
4. B. H. Baden Powell, Hand-Book of the Manufactures and Arts of the Punjab (Lahore: 1872), 168