Step 1:
Prefold over these two lines.

Step 6:
Fold the upper part of the edge straight upwards over the prefolded line.

Step 5:
Press the edge downwards on 3 or 4 more places, see arrows as example.

Step 2:
Roll up the paper and tape or glue the parts indicated by the rectangles together.

Step 4:
Press another spot downwards.

Step 3:
Press this spot downwards.

Step 10:
Make a few Zig Zag folds on the edge, see very short purple lines as example.

Step 8:
Press this part of the tube flat, see arrow

Step 9:
Valley-fold over these two lines, start with the line on the right.

Step 7:
Tape or glue the edges together, see arrows as example.

Step 16:
Press this spot downwards.

Step 15:
Press this spot downwards.

Step 12:
The paper for the cap has the same size as the paper for the tube.
Valley-fold over these two lines.

Step 11:
This part of the tube is done....

Step 14:
Roll up the model, use the size of the tube as guidance. Use tape or glue to connect both ends.

Step 13:
Prefold over this line, it's just a little above the centerline

Step 18:
Make sharper folding lines.

Step 17:
Press the edge downwards on 3 or 4 more places, see arrows as example.