Tribute Summon "Scrap Golem" while "Scrap Searcher" is in the Graveyard.

Next, Special Summon "Scrap Orthros" and use its effect to destroy itself. This will activate effect of "Scrap Searcher," Special Summoning "Scrap Searcher" from the Graveyard.

Then, use the effect of "Scrap Golem" to Special Summon "Scrap Orthros" from the Graveyard. Now you're all ready to Synchro Summon "Atomic Scrap Dragon"!