Preamble.... I’m not a native English speaker, so forgive the mistakes. Or write to me to correct them :). Be kind.
I love Lego, I love to crochet.
I thank Lizzyastro who make the instructable for the doorstop and gave me the idea of doing this box and the permission of doing this instructable.
Given that I’ve done the box and only after I’ve wrote this instructable, I’ve used the photos taken from another box (rainbow box), but it’s the same of the Lego box, the only difference is colours and the lid.
This is my first Instructable.

You can find the Italian version here: http://fabuland.wordpress.com/2012/02/29/uncinetto-e-cucito-scatola-lego/

Materials
An old carpet, moquette, plastic sheets, cardboard or something that, when cut into pieces, can stay up alone
White fabric
Wool or cotton
Needle or sewing machine
Sewing thread
Heavy duty scissors or cutter
crochted/sewing scissors
Hook #4
Stuffing

Step 1: How to Prepare the Stuffing

Decide the measure of the box. Cut the carpet in pieces slightly littler (more or less 0,5 cm littler) than the measure you chose. I’ve done the red one and the rainbow one 11x11x7 cm.

Cut the carpet in squares and rettangles of these measure:
1 square 10,5 x 10,5 cm
1 square 11,5 x 11,5 cm
4 rectangles 10,5 x 6,5 cm

Use a set square to help you cut it.

Note: You can use plastic, if you can cut it, but I prefer something softer. If you don’t plane to use the box in bathroom or kitchen, or where it risks to be wetted, you can use cardboard.

Step 2: Prepare the Pieces of the Carpet

You can avoid this step if the carpet is very clean and/or of a colour that's good with the wool/cotton you choose.

If needed, wash the pieces with laundry soap and a hard brush, wring them and let them dry. Iron them with starch. Cover them with white fabric (or fabric of the colour of the cotton/wool you’ll use) and sew them on the borders.

You really don’t need to be too accurate, these parts won’t be in sight.

In this way the fabric won’t move away. You can iron and use starch to make these pieces more rigid.

I've done the rainbow box sewing by hand, in the red box they're machine sewed.

Step 3: The Platform

Star to crochet 23 chains, turn and do 22 single crochet, 1 chain, turn 22 sc until you’ve done 25 rows. You should have a square at the end: to control this fact, fold it on the diagonal, if it’s a square the sides would overlapping perfectly. If not, continue crocheting or undo some rows. This can change according to the weight of the wool, the hook and how you crochet.

When you have finished the base, do not cut the thread, but go on crocheting on the border: when you’re crocheting on the lateral side, you have to do a single crochet every row. To do all the perimeter you should do 98 sc, because on the corners you should do 2 single crochet in one (inc sc). Do not cut the thread.

You can do another round, if the square is not yet bigger than the littler square of carpet. It should be more or less 1 cm bigger (i.e. if you cut the square 11x11 cm, the crocheted square should be 12 cm).

Note: The number of single crochet you’ll do in this step depends on how you crochet (in Italian we say “how is your hand, if tight or large”) and from the type of wool/cotton you’ll use. Controll the size of your work with the square you cut in step 1.

Step 4: The External Walls

Start to crochet only in back loops, do not more increasing crochet. This will make the crocheting perpendicular to the first part. Do not join the round, work in continuous spirals. Crochet 17 round.

You have the base of the box. You can control if it’s right putting the square and the rectangles in it. I put the rectangles out of the square. If it’s okay, you can go on. Otherwise, crochet some other round until you reach the top of the rectangles.

Step 5: Top of the External Walls

Now crochet only in the back loop, to bent the new part. Do decreasing single crochet on the corners (*18 sc, 1 dec-sc** 4 times from * to **). Finished this first round, do another round, with dec-sc on the corners (*17 sc, 1 dec-sc** 4 times from * to **). These two rounds should be of the same measure as the depth of the carpet. If not, do another round, or undo the last one.

Step 6: Internal Walls of the Box

Crochet on back loop, doing 2 dec-sc on the corner. This will do the internal part of the box. If you prefer, you can avoid this part and re-cover it with fabric. I prefer to crochet all the part because I can stitch them together and the stitches won’t show and it gives the box a fluffy look. >^.^<

Crochet 14 spiral rounds (“tube”). This part should reach the base when you put in the carpet square and rectangles. Crochet this part pulling it toward you. When you’ll finish, you can push it in the box.

Step 7: Inner Base

Without cutting the thread, go on crocheting another square, 18 sc long, attached to the previous tube. It should start on a corner and finish at the other. Crochet 23 rows.

This part should be as big as the littler carpet rectangle.

Step 8: Finishing the Box

Put the littler square and the rectangles in place. Sew this square to the last round of the tube. (You can also do this step while crocheting, using the last sc of the row to sew.)

Sew the internal and external parts with hidden points.

I saw the corners and the side too, the inner part with the outer. This is simple because with crochet the stitches won't show.

Step 9: The Lid

Basically, the lid is done almost the same way of the box.

Start 26 chains. Turn and crochet 25 sc and do 28 row, then go on crocheting on the border as you done for the box, do a increasing sc in the corners. Do not cut the thread.

You can do another round, if the square is not yet bigger than the bigger square of carpet. It should be more or less 1 cm bigger (i.e. if you cut the square 11x11 cm, the crocheted square should be 12 cm). Put this part on the box to check if it’s right.

Start to crochet only in back loops, do not more increasing sc. This will make the crocheting perpendicular to the first part. Do not join the round, work in continuous spirals. Crochet 7 round. You can add a border done in back stitches, if you like. Cut the thread.

Maybe you'd want to do step 10 before doing the rest of this step. I've done step 10 after, but if I'll do another brick, I'll do the knobs first.

Start 23 chains. Turn and crochet 22 sc and do 24 row, then go on crocheting on the border as you done for the box, do a increasing sc in the corners. Leave a long tail. Put the bigger carpet square in the lid and sew this square in it, so you'll hide the big square between the crocheted squares.

Step 10: The Knobs

Doing this step before finishing step 9th will make simpler to sew the knobs on the lid.

Lizzyastro used plastic lids to fill the knobs, I didn’t find (but for real I didn’t look, because I prefer using stuffing because of the fluffy look >^.^<) lids of the right measure. I used stuffing to fill them.

1st round: Make and adjustable ring - there are a lot of tutorial of it on line, but I just used the starter ring for crochet. Crochet 6 sc and pull the ring closed. Work in continuous spirals (6 sc)
2nd round: inc-sc in every sc of the prev round (12 sc)
3rd round: [inc-sc in every sc of the prev round, 1 sc] 6 times (18 sc)
4th round: [inc-sc in every sc of the prev round, 2 sc] 6 times (24 sc)
5th-8th round: work evenly only in back loop.
Stuff and sew on the lid.

Weave in all the ends and enjoy :)