A quick summary of how to look for items with free shipping:
Free shipping within USA isn't the same as international free shipping..
You need to look for items from Amazon (check the shipper - some are Not by Amazon eg something can be sold by another company, eg Cost Buy and fulfilled by Amazon, this won't qualify..)
Eg when you type "garden tools": when the search results come out you need to narrow it down to those with free international shipping to Singapore by checking the box on the left side of the screen:
International Shipping
AmazonGlobal Eligible