Hi @wonderboy 
This is Ellie from BOGOS.io Free gift. Hope my answer can still be relevant to you now.
You can use BOGOS app to set up the free gift offer on your store, so that when customers buy the 1st product, they will be eligible for a free gift. Customers can also choose their preferred gift from a slider, like this:
Or you can also embed the slider right into the drawer cart, so when customers add the 1st product to cart they will immediately see the gift options in their cart.
You can find the app here: https://apps.shopify.com/freegifts?utm_source=social&utm_medium=forum&utm_campaign=post_ellie
Our 24/5 Live chat support is available to help you with any question you need. Or you can reply to me, I will assist you promptly with the setup.
Wish you all the best with the business! 
Ellie from BOGOS.io
If you find this helpful, appreciate if you could give me a Like or accept it as a Solution.