You could always do some math! Dun dun duuuuuun! Hehe
For each oil and for the salt in the original recipe simply divide by 5 and multiply by 3
When you divide by 5, you're taking your 5 lb batch to a 1 lb batch and then multiply by 3 to get your recipe from the 1 lb batch up to your 3 lb batch.
IE (I don't know the actual oils, so just using a generic batch):
Castor Oil 5.49 oz
Coconut Oil, 76 deg 10.98 oz
Olive Oil 21.96 oz
Palm Oil 16.47 oz
= 54.9 oz
Salt (5 cups) = 80 oz (5 lbs) - 54.9 oz = 25.1 oz / 5 cups = about 5 oz per cup
To get a 1 lb batch divide everything by 5:
Castor Oil 1.098 oz
Coconut Oil 2.196 oz
Olive Oil 4.392 oz
Palm Oil 3.294 oz
Salt 5.02 oz
= 16 oz
To get your 3 lb batch, now multiply your 1 lb batch by 3:
Castor Oil 3.294 oz
Coconut Oil 6.588 oz
Olive Oil 13.176 oz
Palm Oil 9.882 oz
Salt 15.06 oz
= 47.97 oz
since it's a tiny bit short AND it's going to the .001 you can probably round up on your measurements and then run those through your lye calculator ^_^