Friends can give each other assemblers through the G5 Friends service. In order for a friend to send you the assembler you need, add it to your wish list in the Collections Window. To do this, tap the green plus sign next to the desired assembler in the Assemblers section of the Collection window.
You can give each friend no more than one assembler per day for free. The assemblers you send to your friends will not be removed from your Inventory.