Poplar doesn't look good stained. It's used in construction a lot for interior trim that will be painted. Has a smooths surface under paint. Doesn't do well with getting wet. Will twist.

Like I said, look for some cheap mahog. You could make some nice enough, if rough, shelves and tables from knotty pine. You can put ribs under it to keep the top fairly flat. Will be good practice.

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1986 300SDL, 362K
1984 300D, 138K