Here's one for you, only any good on big races though.

Select 3 horses. Put on these 3 trifectas
1,2,3/1,2,3/Field
1,2,3/Field/1,2,3
Field/1,2,3/1,2,3

with this combination, you only need 2 of the 3 to place to get the trifecta. If all 3 run places then you get it 3 times.
Will cost $396 for full units or $198 half units (what I had in Melb Cup)

I got this years Melb Cup, paid $1256.55 for half unit. I had Makybe Diva, Vinnie Roe, Distinction. my friend who taught me this got last years Melb Cup ($11000 for half unit) and this years.