I was sitting in the porch with my son when I saw him start to take cans out of the recycling bins. I was about to stop him when I realized he was just placing them on the top of the electric fireplace. Then I realize he'd trying to get ones of all one colour (so he started with 3 gray barqs cans) then he tried to place them in pattern (so 1 gray, then 1 red coke, then 1 gray) when he couldn't reach another coke can he grabbed a black can and started group the cans by colour.

Then my husband came in & took the cans away

Lucas is only 17 months old. I'm quite sure I know what behaviour like this generally means for the future.

Can anyone think of something else I can give him to try to replicate this with out giving him cans? (which are sharp & dirty).

I've never seen him do this with his blocks.

I'm not worried about diagnosis him with anything, I just want to make sure it wasn't a complete fluke. *sigh* my special little boy!

How about what moms have done through the years? Put all your pans or Tupperwear in a cabinet he can access. Let him stack, restack, sort, etc to his hearts content!

He does have a container drawer

But he doesn't stack or sort them like he was the cans, it's not the first time I've seen him do it either. Just it was very obvious this time.

This may sound silly, but I used to do this when I was young with my grandmother's yarn. I'm not sure if this is practical for you, or if a boy would have the same interest. My grandmother was always knitting something so there was always a good supply. She used to help me make balls of yarn from the skeins, and then I'd sort/stack....

He throws I've tried to tape down my ends or stick them right into the middle of the ball but they end up EVERYWHERE & that's not safe for the cats .

I've been wracking my brains too, haven't been able to think of anything.

My son was a sorter (and an organizer...loved to line things up). When he was about your son's age, he became obsessed with matchbox cars. Once we had accumulated several, he started sorting by category (safety vehicles, speed vehicles, etc.). He never went anywhere without one in each hand and several in his pockets.

He also loved to read and sort tiny baby books (about 4" x 4"). He had two sets of different colors (each set covered the alphabet). He would sort by subject, animals, story type, and color of the covers. These were handy for taking places where we didn't want him making a lot of car noises.

Did he see this in action at the grocery store recently ? you could give him small unopened cans, he might enjoy the sounds of the can in particular.
You could try small empty tea tins, we have them coming out of our ears because my ds likes the twinings in the red can with a resealable lid...Dd3.5 is sorting her cars lately, too. Pretty funny when she gets them all 'just so'.