I hope others will chime in as I admit, I have never made petit fours. The site linked below has a video and loads of tips. They looked pretty good! I hope this helps.

From the bottom of the Sprinkle-Bakes Blog:

Tips for Fondant Success:

It is of paramount importance that this fondant stays thin when dipping the cakes. Be sure to work near the microwave so you can quickly heat the mixture during dipping. Alternatively, you may place fondant in a heat-proof bowl and have a simmering saucepan of water on the stove in which to place the fondant when it starts to thicken.
Do not add the food coloring and flavoring to the hot syrup before it has cooled. This will cause the fondant to be grainy.

Dip the imperfect cake cubes first. Every beginner batch has one or two that are lop-sided. These can be âÂÂtestâ pieces so you can learn to gauge the behavior of the fondant before dipping the more perfect cubes.

Have a wet dish towel handy to wipe fondant covered fingers between cake dippings.

Fondant can be cooled and refrigerated for 24 hours before using. It will completely harden, but can be re-heated in the microwave (or stove top--just donâÂÂt boil it) until thin and pourable.

Instead of dipping cakes in the warm fondant, you may choose to place it in a 4 cup glass measure and pour it over the cakes. If you have success with this method--God bless you. The dip/spoon method works best for me because I know the sides of the cakes will be evenly coated without wasting too much fondant--but if you find my method too messy or complicated, experiment and find what works best for you.

DonâÂÂt be discouraged if your first batches of cakes are messy and lumpy. This is a recipe that takes practice, so be patient with yourself.

Here is a link that might be useful: poured fondant and petit fours

Many thanks, Rob!