This is an easy tutorial to make a pattern and sew a loose spaghetti strap dress.
Step 1 Make the pattern for the front bodice and back
You need 4 front pieces – 2 outer pieces and 2 linings. The linings should be cut carefully as mirror images of the top piece
The second piece is the back piece. Cut that on fold as per the pattern given below
A-B = 1/4 of Bust round + 1 1/2″.
C-D = 1/4 of bust round + 1″
Step 2: Cut out two spaghetti straps
Cut 2 bias cut fabric pieces of 12 inches length and 2 inches wide. You can attach adjusting buckles on your strap if you want to be able to adjust them Make them into thin fabric tubes first. Keep the fabric folded by the center, right sides together and stitch along the middle. Do not cut the seam allowance. Using a needle and thread anchored on one edge turn the tube right side out. The seam allowance will form the bulk inside your strap. Use the tutorial here for making fabric tubes for more details. Then stitch along the edges to the make the strap more sturdy
Step 3 Sew the darts
Mark two 2 inch long darts which are 3/4 inch wide along the armhole side. Mark this on all the 4 pieces (linings and outer pieces) of your front bodice. Sew the darts from the wrong side on all pieces, including on linings
Step 4 Join the straps
Keep the strap along the top edge sandwiched between the front piece and lining, both pieces right sides together. Stitch along the sides, including the top edge.
Turn the piece right side out.
Do this for both the sides
Step 5 Join the two pieces
Step 6 Cut the skirt pieces
You need two skirt pieces. Fold two fabric pieces by the center and mark A-B as the top edge and CD as the bottom edge.
A-B should match 1/ 2 of the bottom edge of your bodice. Use this measurement for back and front skirt pieces.
C-D (Hem edge) = Hip measure + 4 “
Step 7 Join the skirt piece to the front bodice
Step 8 Join strap to back bodice
Take the strap, other edge and keep it inside the folded edge of the back bodice. Pin in place. Fold again so that it is fully enclosed
Stitch the strap and top edge in one go. Make x shape stitch to reinforce the strap
Step 9 Join the back bodice to skirt.
Step 10 Join the side seams of front and back
Stop some 5 inches short of the bottom edge. This is for making slits along the bottom edge on both sides
Sew the slits by folding the seam allowances to the inside twice
Step 11 Finish the bottom edge.