SAMPLER - 4-Shaft, 4-Block.
Warp-faced Rep Sampler for 4-Shaft Weavers
Warp-faced rep is characterized by "ribs" formed by the alternation of thick and thin picks of weft. A thick pick is followed by a thin pick of weft on the opposite weave shed. Below is a thread by thread draft for a 4-shaft, 4-block rep weave sampler based on a point twill threading.

The pattern color is turquoise, and the background color is lilac. There are four different threading blocks. The pattern color (turquoise) alternates with the background color (lilac) throughout the entire threading. Block 1 is threaded on shafts 1 and 3, with turquoise threaded on shaft 1and lilac on shaft 3. Repeat this threading for desired width of the block. For instance, if you are using 3/2 cotton, with a sett of 30 ends per inch, you might decide to thread an inch of Block 1. This means you'd thread turquoise on shaft 1 and lilac on shaft 2, repeating 15 times for a total of 30 ends.
Block 2 is threaded on shafts 2 and 4, turquoise on shaft 2, lilac on shaft 4. Repeat this threading for desired width. If Block 2 is another inch wide, repeat the threading sequence 15 times.
Block 3 is threaded on shafts 3 and 1, turquoise on shaft 3, lilac on shaft 1. Repeat for desired width.
Block 4 is threaded on shafts 4 and 2, turquoise on shaft 4, lilac on shaft 2. Repeat for desired width. Notice that the pattern colored end is threaded on the shaft which gives it name to the Block.

Notice the threading blocks ascend in the order of 1, 2, 3, 4, and descend 3, 2, 1. This is a threading based on a point twill ... 1 2 3 4 3 2 1. If you saw this draft as a profile draft, it would look like the diagram below. I could have shown the draft in graphic black and white, but chose to make the pattern color turquoise, and the background color lilac to correspond with the thread by thread draft above.

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Now look back at the thread by thread draft to see how it corresponds to the profile draft.
Notice also that in the thread by thread draft, there are rectangles under the tie-up box ... tall rectangles indicate a thick pick, while narrow rectangles indicate the thin pick which locks it into place. When shafts 1 and 2 are raised for the thick pick, the other two shafts (or opposite shafts) 3 and 4 are raised for the thin pick. You can repeat these two combinations for the "height" of the thick and thin picks that you want. In fact, you could weave the whole textile in one stripe combination. Below on the left is a profile draft showing the four different stripe combinations you can create with this threading. When written as a profile draft, only the "thick picks" are indicated. The thin picks are "implied". So if you raise shafts 2 and 3 for the thick pick (as in the second example below on the left), you'll need to lift the remaining two shafts for the thin pick, namely shafts 1 and 4. On the right side are more profile treadlings to try out.

Suggested setts for cotton:
carpet warp: 30 to 36 epi
3/2 cotton: 30 epi
5/2 cotton: 36 epi
8/2 cotton: 48 epi
10/2 cotton: 54 epi
Thick pick weft should be at least seven times heavier than warp. If using 3/2 cotton, try seven strands 3/2 cotton wound together on one shuttle, and 5/2 cotton as thin pick. There are also many different rug weight cottons to sample. Look in your stash for other substitutes.You can also use cloth cut into strips.
The number of thick and thin picks thrown for each pair of shed openings depends on how high you want that block to be. It's weaver's' choice.