I changed the model of thing:107862 to have slots where 1 eurocent coins can be inserted as weights, instead of the original holes that should be filled with something random. Sadly, this does influence airflow and the boomerang doesn't fly as good as the original design. But it still worked and is fun to play with. I am not completely satisfied with the slots, but this is as good as it get's on my Replicator 2. Ideally the boomerang is to be printed slightly larger thant my printbed allows, so the slots can be embedded deeper. But I couldn't test with that. I might try another design where the coins are fully enclosed in the model and need to be inserted during print. You need to print this on 0,1mm layer height, otherwise the coin slots won't be fully covered due to the thin top. I used 3 shells and 15% infill for strength, but 2 shells and 5% should work as well.