Messenger's Mail Bag

Important!
• Steam must already be able to trade. (Otherwise, you will get a 3-7 day trade hold from Steam)
• Set your Steam inventory to public.

Trade offer link:
Inventory - Trade Offers - Who can send me Trade Offers? - Scroll down - Trade URL - Copy

How to set your Steam inventory to public:
Profile - Inventory - Inventory Privacy Settings - Inventory: Public