Separate objects joining- preparing for 3d printing

Hello I've made with Djordje's help some excercise. Balls distributed on surface. Many of them are not joined with other. Finally I want to prepare such object for printing, thats why it's necessary to join them. Every sphere must be joined with others. I'm waiting for your sugestions guys ! 

On picture I draw the example what I'm looking for. Red lines are the pipes joining center points of balls. The green elements are the example of smooth surface joining balls together. Theese are just examples, I'm not sure what is possible. 

sphere.3dm

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