These two triangular pieces are functionally the same as this earlier printable but keep the tabs hidden instead of making them visible like jigsaw pieces.

Because the tabs need to be printed with overhang, they are given an upward slope. They are closer to horizontal than the recommended 45° but print without problem. I am using a Flashforge Adventurer 3 Pro 2 with PLA. Unfortunately, they're a little fragile, but will not break as long as you are careful not to force them in the wrong way.

Each edge matches itself when flipped. In addition, the external edges match kite and dart edges as expected. The simplest way to see that this is equivalent to a Penrose tiling is to attach pairs of identical triangles along the internal edges, which use double tabs. Then the resulting kites and darts fit according to conventional matching rules.

Kite and dart: 

These same triangles can also be combined into rhomb tiles. To do this, print one color using kite halves to make thin rhombs. Then print another color of dart halves and kite halves that can be fit together into thick rhombs as follows.

Note: Before assembling triangles into larger tilings, I recommend fitting them together individually. This will remove any excess material and make them easier to snap together later.

A Penrose tiling can be built by constructing a series of triangles, each composed of its two predecessors like a Fibonacci sequence:

Once complete, 10 copies can be combined into a symmetrical tiling like this.

Using a different color scheme, the identical tiling can be made with thin and thick rhombs.

As with the previous version, these triangles can be grouped into different ways of representing Penrose tilings.

See  https://www.printables.com/model/832709-flippable-robinson-triangles-penrose-tiling-variat and https://www.printables.com/model/905407-robinson-triangles-alternative-version for information about related tiles.