I wanted to create a custom set of cards to use and went about designing them myself. 

I used Aseprite as my drawing tool. The canvas size I used is 31x41 pixels (this includes the black border). All letters (and suit letters) are 3x4 pixels (expect "JOKER" cards which are 3x3 pixels). The suits are 5x5 pixels each.

I started off by using Balatro's colours as my suit colours, as I find those suit colours to be very pleasing to the eyes. I love how Balatro slightly separates the "red" suits and "black" suits from each other by giving them a slightly different tone of red and black respectively that helps distinguish them but keeps similarity in originality. But I also really liked the high contrast colours as it makes differentiating suits a whole lot easier, especially in pixel art where shapes can be very similar to each other.

The number cards were very easier to do as they just required plopping the same shape in specific patterns on the card. I used markers as shown in Figure 1 to help line up all the suit shapes. Aces were also easy and fun to do as I got to draw a big suit shape. The maximum size is 15x13 pixels (Ace of Hearts sprite dimensions. All other Ace sprites are slightly thinner than 15 pixels wide). Aseprite's custom brush tool helped immensely with painting the sprite shapes.

For the face cards, I used the vertical mirror tool to draw a mirrored version of the face simultaneously before mirroring the bottom face horizontally to create the same effect as on traditional deck of cards (Figure 2). I wanted to mimic Reigns' art style as I really like the simple face design with tall eyes and half the face being shrouded (Figure 3). All my face cards have those tall eyes and the spades all have a half dark face, with all other suits having one face card having a half dark face. You might also notice that all the spade's dark half is on the left side of the face while all the other suits have the dark half on the right side of the face.

The Jokers were a little hard to conceptualise, especially as they don't follow the mirrored art style as the face cards. I knew I wanted to do just a top-half as I wouldn't have enough room to do a full-body design. I also wanted to try and keep the Reigns' theme going with the face. I first looked at Balatro's Jimbo card (Figure 4) as a reference and did some initial designs around that, but then I came across Figure 5, which was near perfect of what kind of Joker card I wanted. It was a top-half painting that also had that half dark face that I wanted. I also used the 3x3 pixel letter template for "JOKER" in Figure 5, as 3x4 pixel letters caused the "JOKER" text to nearly hit the bottom, which did not look pleasing and made the whole thing look extremely busy.

As for the card backs, I just went some random designs. The first was the one with the triangles in the bottom-right of Figure 6. I saw a similar design elsewhere where 3 triangles were interlocked with each other and made the illusion that they actually created this greater complex shape. It was tricky getting the triangles lined up correctly, but I am happy with how it turned out. As for the card back above, I just created a flower shape with 8 petals in the centre and branched out the design from there to where it is. I also added a decorated border with triangles again because I was obsessed with triangles for some reason.

The final design of the cards is as shown in Figure 6.