A 3x3x3 solid can be filled with three copies of a tetracube and three copies of a pentacube.

Below is a catalog of the tetracube/pentacubes pairs for which solutions exist. The catalog links to solution drawings whenever there are three or fewer solutions. For example, to see the two solutions for three L-tetracubes and three U-pentacubes, click the solution drawings link. In the bottom half of the linked window you will see a frame for each solution. Within the frame you can click on the next (or previous) link to add (or remove) a piece from the drawing.
1: 3 L-tetracubes, 3 Z-pentacubes
1 solution

3×
solution drawings
2: 3 T-tetracubes, 3 P-pentacubes
1 solution

3×
solution drawings
3: 3 branch-tetracubes, 3 W-pentacubes
1 solution

3×
solution drawings
4: 3 L-tetracubes, 3 U-pentacubes
2 solutions

3×
solution drawings
5: 3 L-tetracubes, 3 L2-pentacubes
2 solutions

3×
solution drawings
6: 3 L-tetracubes, 3 N2-pentacubes
2 solutions

3×
solution drawings
7: 3 branch-tetracubes, 3 L2-pentacubes
2 solutions

3×
solution drawings
8: 3 branch-tetracubes, 3 L4-pentacubes
2 solutions

3×
solution drawings
9: 3 L-tetracubes, 3 N1-pentacubes
3 solutions

3×
solution drawings
10: 3 left screw-tetracubes, 3 P-pentacubes
4 solutions

3×
11: 3 branch-tetracubes, 3 P-pentacubes
5 solutions

3×
12: 3 L-tetracubes, 3 A-pentacubes
6 solutions

3×
13: 3 square-tetracubes, 3 V-pentacubes
many solutions

3×
14: 3 L-tetracubes, 3 P-pentacubes
many solutions

3×
15: 3 L-tetracubes, 3 Q-pentacubes
many solutions

3×
16: 3 L-tetracubes, 3 L4-pentacubes
many solutions

3×
17: 3 T-tetracubes, 3 U-pentacubes
many solutions

3×