Scoop ice cream: Line two large plates with parchment paper or waxed paper. Place plates in freezer for 15 minutes to chill. Use very small ice cream scoop to make about 16 balls, each with about 2 tablespoons of ice cream, and place them on two chilled plates. Lightly cover plates with plastic wrap and freeze until ice cream is very firm, at least 1 hour.
Dip ice cream in chocolate: Melt chocolate with oil and stir until smooth. Cool completely to room temperature. Remove one plate of ice cream from freezer and, working quickly, use two forks to dip and roll one ice cream ball in chocolate to cover. Pick up ball by sliding it onto one fork, and let excess chocolate drip back into bowl. Return bonbon to lined plate.
Garnish bonbon: If desired, immediately sprinkle bonbon with nuts or coconut. Remeat dipping and garnish ice cream balls remaining on plate, one ball at a time. Return first plate to freezer. Remove second plate of ice cream balls from freezer and repeat process to make 8 more bonbons. Freeze bonbons until firm, at least 1 hour or up to 1 day, before serving.